Up-to-date standards are offered for checking compliance, and it provides a cost-effective way to scan a site for compliance. There's services out there where it'd cost more than $150 (the current cost of a 1 site 1 year license) for the size of the sites I'm working with. I'm very happy to see this offering in the first place, and it's even nicer to see how thorough it looks to be. Of course, it's not perfect so I'd love to see more of the WP.org listing fleshed out (the developer author/contributor mention is missing, etc.), I'd love to see the free version on GitHub (or similar for community development assistance [I have a few things I'd help with] which is very nice to see in a WP.org listing to show there's support / ongoing development for the plugin), and of course I'd love to see the server-side checker come to feature-parity with WAVE (currently WAVE is showing a few things the server-side checker doesn't have [color contrast, etc.]) Keep up the great work!

Nice Article! It is very important to work under guidelines if you don’t want to get sued and don’t want to pay the penalties. But more importantly it is better to give each user hassle free user experience over your website. Being ADA Compliant means your website works well for people with disabilities and they can easily access and navigate your website.
Automated testing is the first step toward determining if your website is accessible to people with disabilities, including those using assistive technologies like screen readers, screen magnifiers, switch controls, and others. The free testing tools on this website will give you an idea of whether your website is compliant with laws like Section 508, the Americans with Disabilities Act (ADA), and the 21st Century Communications and Video Accessibility Act. If you find you have many violations, Level Access has experts that can help you reduce your legal risk.

This guidance document is not intended to be a final agency action, has no legally binding effect, and may be rescinded or modified in the Department's complete discretion, in accordance with applicable laws. The Department's guidance documents, including this guidance, do not establish legally enforceable responsibilities beyond what is required by the terms of the applicable statutes, regulations, or binding judicial precedent.

Additionally, in February 2018, Congress passed the ADA Education and Reform Act, a bill designed to make it harder for disabled Americans to sue businesses for discrimination. Republican lawmakers who wrote and passed the bill argue that the law will help curb “frivolous” lawsuits, while opponents have argued that this law will gut the ADA, essentially giving businesses little reason to follow the ADA guidelines at all.
Regarding examples of accessible websites, I would suggest the Accessiweb gallery: http://www.accessiweb.org/index.php/galerie.html. Accessiweb is a reference list 100% based on WCAG2, and they deliver quality marks (the "Accessiweb label") upon website owners solicitation. The website undergoes a thorough manual review (on a carefully defined 10-page sample, more or less), and it gets the label only if it's flawless on every page. The level is reflective of the number of defects found and not corrected. Bronze is exactly equivalent to level A, Silver to AA, and Gold to AAA. So getting a Silver label means all A and AA tests were passed on all of the sample. Bronze, two stars: All A tests were passed, plus 50 to 75% AA tests. And so on.

I should mention one caveat to all of this. Businesses that are required to comply but don't have the ability to bring their websites into compliance can provide an accessible alternative to provide the same information, goods, and services that they provide online, like a staffed phone line. The trick, however, is that this option has to provide at least equal access, including in terms of hours of operation. And, as we know, the internet is around 24/7, so good luck with that. 
The free nationwide telecommunications relay service (TRS), reached by calling 7-1-1, uses communications assistants (also called CAs or relay operators) who serve as intermediaries between people who have hearing or speech disabilities who use a text telephone (TTY) or text messaging and people who use standard voice telephones. The communications assistant tells the telephone user what the other party is typing and types to tell the other party what the telephone user is saying. TRS also provides speech-to-speech transliteration for callers who have speech disabilities.
You probably won't have to check your site with all of the available evaluation tools out there, but it is a good idea to do so for the most common web browsers. Just as accessibility software makes it easier for people with disabilities to navigate the Internet, these tools make it easier for developers to ensure accessibility from the start. When you think you've mastered it, go back through the Section 508 compliance checklist to ensure you've met every goal.
When you insert an image into a post or page, consider providing a rich description for the caption that will improve the reading experience for everyone, but especially folks who can’t see the image. Be creative. Instead of “My son on his swing,” try “My son is playing on his favorite swing. His face is filled with pure joy on a beautiful Spring day. Perfection.” The goal here is to convey the feeling of the image.
Reha opened the session by asking everyone to imagine they’re on a train platform, heading home from work, thinking about the great day they had and the presentation they knocked out of the park. They’re toying with their coffee cup, waiting for the train, when all of a sudden, a man walks up, puts a $5 bill in the cup, says “God bless,” and walks away.
Accessible design benefits all users and creates market opportunity, Reha said. She continued: “Access to information online is everywhere, so it’s easy to take for granted that it’s available to everyone, but it’s not. Such access is incredibly important for people with disabilities because it lets them become independent and improves their quality of life.”
@Rick, I didn't specifically look at doctype, but Steve Faulkner did in his original article (see the link at the top of this post). He found that 101 of the 130 pages containing role="main" (78%) used the HTML5 doctype, which of course leaves 22% that didn't. I do recommend using ARIA even if using an earlier doctype. Validation is important, but if validation and accessibility conflict, I think most would agree accessibility should trump validation. Assistive technologies that support ARIA landmarks do so regardless of doctype, and otherwise the presence of these role attributes has no ill effects in any user agent.
Case law has been the most helpful in illuminating the implications of the ADA for websites.There have been lawsuits involving companies like Expedia, Hotels.com, Southwest Airlines, and Target as defendants and primarily featuring accessibility organizations as plaintiffs. These cases had mixed results, but each helped clarify the ADA's jurisdiction on the web. 
A critical and often overlooked component of ensuring success is comprehensive and ongoing staff training. Covered entities may have established good policies, but if front line staff are not aware of them or do not know how to implement them, problems can arise. Covered entities should teach staff about the ADA's requirements for communicating effectively with people who have communication disabilities. Many local disability organizations, including Centers for Independent Living, conduct ADA trainings in their communities. The Department’s ADA Information Line can provide local contact information for these organizations.
Title III of the Americans with Disabilities Act (ADA) requires that businesses and nonprofit services providers make accessibility accommodations to enable the disabled public to access the same services as clients who are not disabled. This includes electronic media and web sites. While the ADA applies to businesses with 15 or more employees, even smaller businesses can benefit from ensuring that their websites are ADA compliant. Doing so opens your company up to more potential clients and limits liability. Web developers should include ADA compliant features in the original site and application plans.