This past September marked the first time a judge ruled that the ADA applies even to businesses without a physical location. Scribd, an e-book subscription service is considered to provide "a place of public accommodation." Their services are not accessible to blind persons because they cannot be read with a screen reader. The judge reasoned, "Now that the Internet plays such a critical role in the personal and professional lives of Americans, excluding disabled persons from access to covered entities that use it as their principal means of reaching the public would defeat the purpose of this important civil rights legislation."
The gray area is a matter of scale and purpose. If you have a small business which serves as specific market it's a good idea to make the site as user and disability friendly as possible. If, however, your market serves segments with a likeliness to have various handicaps or disabilities you should address that with an ADA Compliance review of the site. Also consider the scale and purpose of an organization. Publicly traded large businesses need to concern themselves more than a single location family owned retailer and if someone sues your flower shop because the text was too small or didn't have "image alt tags" causing them distress... That's pretty frivolous and would likely not stand.

In an August 2016 case involving the University of California Berkeley, the DOJ ruled that the public university was in violation of ADA Title II (similar to Title III but it instead applies to government organizations) because their YouTube channel’s videos didn’t include captions for hearing impaired visitors. The DOJ found this to violate the ADA as deaf users did not have equal access to the online content.
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.