> What if tomorrow some change of parameters makes my business impossible? I'll go out of business. That's always an option.
Yes and no one can sue you for going out of business. But you can be sued for violating a law while your business is in operation.
> Dealing with every possible risk ahead of time generally isn't an option.
No you need not if you use standard software development tools that do it for you. You would need to worry about it if you plan to implement everything on your own.
> If this was a real problem for software in general, why is there no cottage industry of shady lawyers using people with disabilities to sue software vendors in particular? There's obviously lots of software that is not accessible, or not accessible enough.
When there is a clear law that states that you have to make your software accessible you have no choice but to implement accessibility. For personal use you need not. For open source projects, the implementation rests on the shoulders of those using the project for end-user facing software. You can get away with it for a while, just like you can get away with using pirated software. But then law will catch up anyways. Just because there is no precedent set doesn't mean that it is legally allowed. Would you want to be the first test case? A scapegoat? I bet not!
As far as why there are no cottage industry of shady lawyers: Maybe those shady lawyers have bigger fish to catch. Maybe there isn't much awareness about it in the legal circles. Could be variety of reasons why.