I wonder if there is a good rule of thumb for what software and features are acceptable to not be accessible? What does it mean for a drawing program to be accessible by the legally blind? You can follow accessibility guidelines (for UI navigation and so on) but does that mean you made the program accessible if the bulk of the operations you can actually do in the software - draw - still requires seeing what you are doing? Are you expected to invent workarounds that allows people to use your software, or can you assume that "nah, no blind person is likely to be drawing anyway"? It seems there is a gray area where it's just not economically feasible to add some extreme bespooke types of accessibility, but at the same time not doing it will make it self fulfilling - of course no blind people will draw in drawing programs so long as they don't get the tools.
Well, the law provides for a number of balancing tests to ensure that a court will respect the rights of all parties. A rule of thumb is unlikely to be specific and precise enough for any practical use. For specific details, consult an attorney.
Since it only applies to "public accommodations", it's highly unlikely that a drawing program will be covered, unless it's tied to a good, such as if you can have the drawing printed up for you.
