When I worked at the university, doing their websites, I simply could not get accessibility on anyone's radar: my boss, the people in the power structure nearby, the awful design people who saw the Web as a means to deliver photography and, if forced, text in a brochure format.
I had my own tools -- making sure the XHTML and CSS were valid, testing on multiple browsers, testing on lynx, a separate PC with jankety mouse settings to make it hard to click and a few sets of glasses to distort my vision, etc. Accessibility has to be a first class citizen when you make that template, it cannot be bolted on later. And it means being rigorous: fill out that alt text, test that tab order. I had no budget, just raw stubbornness and a willingness to be the bad guy.
It was continually infuriating that nobody cared about people with low vision, or crap bandwidth, or colorblindness, or motor tremor, because, barring an early death or really great health, we're all liable to enter one or more of these groups with time.
The last, sad argument I had, which worked and was shameful, is that good accessibility almost automatically makes your SEO better. It is both true and mildly upsetting to have to resort to, I felt like I was saying "... also, orphans are more gamey than other kinds of meat."
I don't think you can Javascript your way out of these very real problems. What is needed is an Accessibility Czar for your web properties, who can veto anything, who can pull off their shoe and pound it off the table and force someone on the Design Team to wear a little duncecap as they read out an article on Target getting mauled by the ADA for their screwups.