I have a membership website teaching martial arts. It is accessible only to people who pay a monthly membership fee. I recently had a gentleman in Malta ask if I could make more than 850 videos on the site accessible to him (he is visually impaired). That is an impossible task for a one-man business. If I understand this article correctly, my site is not required to be accessible?
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.
Title III of the Americans with Disabilities Act (ADA) prohibits discrimination on the basis of disability in places of public accommodation, including restaurants, movie theaters, schools, day care and recreational facilities, and doctors’ offices. All public places, as well as privately owned commercial facilities, are required to comply with ADA standards.