@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.
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.

When the Americans with Disabilities Act (ADA) was first passed in 1990, the internet had yet to take off. However, the ADA has realized the importance of including online spaces within its parameters. If your business is considered a ‘place of public accommodation,’ then your website must be ADA compliant. Multiple rulings from judges have set legal precedent that websites must be accessible and are at risk of heavy fines and penalties when they are found not compliant. Winn-Dixie is the latest business to learn this the hard way.

Luckily, the international nonprofit World Wide Web Consortium (W3C) brings together smart people who develop open standards to ensure the long-term growth of the Web. They produce recommendations for making websites fair and equally accessible for the highest number of people possible. Their Web Content Accessibility Guidelines (WCAG) 2.1 offer clear guidance for web developers to achieve ADA compliance.

As organizations around the world scramble to bring their sites into compliance with the World Wide Web Consortium’s Web Content Accessibility Guidelines (WCAG), focus on other, preexisting accessibility regulations has also intensified. The United States’ Americans with Disabilities Act (ADA) is one of the most visible and complicated pieces of accessibility legislation. Let’s look at some of the ins and outs of what an ADA compliant website means today. Or, if you're interested in seeing the nitty-gritty details of your site's accessibility, request a free website audit report using the form on this page.

For people who are deaf, have hearing loss, or are deaf-blind, this includes providing a qualified notetaker; a qualified sign language interpreter, oral interpreter, cued-speech interpreter, or tactile interpreter; real-time captioning; written materials; or a printed script of a stock speech (such as given on a museum or historic house tour). A “qualified” interpreter means someone who is able to interpret effectively, accurately, and impartially, both receptively (i.e., understanding what the person with the disability is saying) and expressively (i.e., having the skill needed to convey information back to that person) using any necessary specialized vocabulary.
Legal precedent is changing, and ADA compliance related lawsuits are becoming more successful, and the courts are seeing more of them as a result. Title III of the Americans with Disabilities Act pertains to private sector businesses. Lately, those protections are more frequently expanding into digital territory as web and mobile applications become more necessary in our day-to-day lives.
Through the Americans with Disabilities Act (ADA), our nation committed itself to eliminating discrimination against people with disabilities. The U.S. Department of Justice’s (DOJ) Civil Rights Division is proud to play a critical role in enforcing the ADA, working towards a future in which all the doors are open to equality of opportunity, full participation, independent living, integration and economic self-sufficiency for persons with disabilities. 

This is particularly important when working for a government agency or government contractor, as these organizations must follow web accessibility guidelines under Section 508 of the Workforce Rehabilitation Act of 1973. Although ADA and Section 508 compliance are different, the published checklist for Section 508 compliance offers insight into ways to make websites accessible for people with disabilities, and thereby work toward ADA compliance.
Luckily, the international nonprofit World Wide Web Consortium (W3C) brings together smart people who develop open standards to ensure the long-term growth of the Web. They produce recommendations for making websites fair and equally accessible for the highest number of people possible. Their Web Content Accessibility Guidelines (WCAG) 2.1 offer clear guidance for web developers to achieve ADA compliance.
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!
In court, Netflix tried to argue that websites should not be part of ADA compliance regulations, as there is no physical structure / location. They also argued that websites should not be in scope of ADA as there is no public component (the original ADA compliance law specifically called out that ADA rules apply primarily to services, locations, and products that are supposed to be open to the public).
Not to be outdone by their Southern neighbors, the Canadian government site is highly accessible. The home page is a simple page, beautiful in its perfect symmetry between English and French. The default language as specified on the element is English (lang="en", hey they had to pick one) but all French content is marked up with lang="fr". It's actually quite pleasing, and very Canadian, to listen to this page with JAWS as it alternates between the two languages.
We compared the Google website analytics from July of 2015 to July of 2017, after the launch of VisionCorps’ new website. Their redesign not only made the site ADA compliant, but also optimized the website for better search engine rankings and user experience. The redesign helped increase the number of visitors coming to the website on a monthly basis, the amount of time a visitor spends on the site, and the number of pages viewed in total. Here are the results.
Enough Time: Users have sufficient time to read and use the website’s content. If part of the website has a time limit, users are able to turn off the time limit, or they can adjust or extend it to at least ten times the default limit (unless the time limit is essential to the website’s functionality, such as auction websites like eBay). Content that moves, blinks, or automatically updates can be paused or stopped unless it’s essential to the website’s functionality.
The ADA requires that title II entities (State and local governments) and title III entities (businesses and nonprofit organizations that serve the public) communicate effectively with people who have communication disabilities. The goal is to ensure that communication with people with these disabilities is equally effective as communication with people without disabilities.