Government Code §11546.7 – The requirement that state agency heads certify, every two years, that their agency’s website meets the Web Content Accessibility Guidelines, Version 2.0 or a subsequent version, at Level AA or higher, and the requirements of Sections 11135 and 7405 of the Government Code. Created by AB 434 (Baker, Chapter 780, Statutes of 2017), and sometimes referred to as AB 434.
Leading web developers have been pioneering accessibility and publishing standards since 1994. In 1999, the Web Accessibility Initiative (WAI) and the World Wide Web Consortium (W3C) created the Web Content Accessibility Guidelines (WCAG). In essence, the people who determine how the internet is written came together to advise web developers on how to make websites accessible not only to people with disabilities, but to all web users, including those with highly limited devices.
ADA Compliance is not exactly new, but there is a noticeable increase in lawsuits. but the most important thing you can do to be ADA compliant is to make your website accessible to people with sensory disabilities like deafness or blindness. This includes alternate text for images and media that are more than decoration, like infographics and photos of things that explain or pertain to website content. This is most important if your website represents a public physical location, like a hotel or store of some kind. Because these lawsuits are usually pursued in the necessity, where people with disabilities really need access to such a business and can't obtain it.

Yes, in time non-ADA compliant websites will be penalized in the search engines. It's already on their radar. But for now they are still negatively affected, just in an indirect way. Live traffic behavior (user experience) is now factored into Google's algorithm and is a ranking signal. Negative user interactions absolutely have negative affects on rankings.
The Americans with Disabilities Act (ADA) prohibits discrimination against people with disabilities in several areas, including employment, transportation, public accommodations, communications and access to state and local government’ programs and services. As it relates to employment, Title I of the ADA protects the rights of both employees and job seekers. The ADA also establishes requirements for telecommunications relay services. Title IV, which is regulated by the Federal Communications Commission (FCC), also requires closed captioning of federally funded public service announcements.

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.
The fact that an ADA compliant website can increase your target audience by millions is just one reason to make your site more accessible. Another benefit is that not only will you get more customers, but those customers will also know how valuable they are to your business. After all, they might have gone to a few other websites that were not ADA compliant, disappointed each time that they couldn’t access the content, until they got to your website.
If you use outside resources for your web needs, or have a dedicated web person or company, call them immediately. If you have a department or staff, even better. But— if you are working on your own, you would do yourself and your business a favor to contact a reputable web developer to discuss how to make your site accessible and avoid possible lawsuits. The older your website, the more likely it is that it is NOT compliant. Take action now!
In a society in which business is increasingly conducted online, excluding businesses that sell services through the Internet from the ADA would ‘run afoul of the purposes of the ADA’” in that it would prevent “‘individuals with disabilities [from] fully enjoy[ing] the goods, services, privileges, and advantages, available indiscriminately to other members of the general public.

I have previous experience with a company that sold a platform to help alleviate ADA compliance issues on websites. From my understanding litigation is being brought to a few industries with it beginning to trickle down into others. Government agencies, education, banking, and law firms were some of the early initiators that were paying more attention to ADA before any lawsuits approached their door.
Your site would need to have a text only option, with all functionality accessible through a keyboard for visitors with mobility issues. Once you make these and other changes to meet ADA guidelines, your site would need to be tested by a website development company familiar with ADA compliance issues to be sure that visitors who use assistive technology such as screen readers are able to access your web content fully.
HTML tags – specific instructions understood by a web browser or screen reader. One type of HTML tag, called an “alt” tag (short for “alternative text”), is used to provide brief text descriptions of images that screen readers can understand and speak. Another type of HTML tag, called a “longdesc” tag (short for “long description”), is used to provide long text descriptions that can be spoken by screen readers.