This is one thing that the big dogs, Microsoft, and Apple have been good at since the early '90s. For all their faults, they take accessibility seriously.
I know a blind guy who uses iPhones exclusively. How he manages to understand speech that fast is beyond me, but dedicating resources to accessibility when it's such a tiny market share is nice of them. But now that I think about it, are they being mandated under ADA? I honestly don't know.
No, they are not being mandated. It basically boils down to Jobs declaring that accessibility is an exceiption to ROI. IOW, realising its a kind of social responsibility. Besides, Microsoft took a long time to provide something by default, they let other third parties sell screen readers for big money to poor people. Apple always did both built-in, the API and the screen reader (frontend). Microsoft created Narrator, their own front-end, just a few years ago.
I tried to Google what Jobs said about accessibility... I only found what Tim Cook had to say:
"When we work on making our devices accessible by the blind, I don’t consider the bloody ROI (...) The company does a lot of things for reasons besides profit motive. We want to leave the world better than we found it."
It may well be that Apple is special, but in general, large software companies are motivated to care about accessibility primarily by the prospect of lucrative government contracts, for which there are usually mandated (by law) accessibility requirements. The problem for smaller companies is that accessibility doesn't scale down well - you need a lot of upfront investment (education, processes, testing etc) to get anywhere at all at first, but then all that remains useful for many more projects to come.
I read somewhere that screen readers look for a flashing vertical line, to detect the caret position in systems that don't expose it via the OS's APIs. I can't find a reference for that right now, though.
I'd argue that accessibility helps everyone, and is thus a positive to ROI. You know those low contrast text/background sites everyone here complains about? Yep, those are not accessible, and probably end up with less readers as a result.
I know a blind guy who uses iPhones exclusively. How he manages to understand speech that fast is beyond me, but dedicating resources to accessibility when it's such a tiny market share is nice of them. But now that I think about it, are they being mandated under ADA? I honestly don't know.