GNU/Linux distributions provide great advantages over proprietary alternatives for people with disabilities. All the accessibility tools included in Linux are open source, meaning their code is readily available if you want to examine or improve it, and cost nothing.
Because disabled people are so looking for a DIY solution. I'll give you the one about cost, but aids for the disabled are usually sold or given away far under their actual cost due to ideal organizations, corporate PR, government aid and so on unless you're making a business specifically for the disabled.
Developers who do not depend on assistive technologies tend to forget - or don't know - that a disabled person might want to use their application, read their web page, and so on. ... The problem is not necessarily that developers do not care.
Oh please, the open source community is 95% driven by scratching your own itch. Very few do any real effort to make it easier for other people to use in general, disabled or not. Which of course doesn't mean that we're heartless bastards, we do care that there are children starving in Africa and a blind guy who can't use your app. Just not enough to ever get around to it.
Rather, it's is that accessibility is highly specialized and requires someone with knowledge in the area, regardless of platform.
Yes, but it's usually not rocket surgery if you care enough to explore it. The few times I've dabbled in it I've found that often takes a lot of effort that doesn't benefit anyone but the disabled, the way a wheelchair user needs a ramp where a step works fine for everybody else. Or in other words, even if you know what you're doing it still takes time, that I certainly wouldn't want to spend on a hobby project.