Also the issue of accessibility is unlikely to be even thought of unless it is an issue for the thinker. I've occasionally seen a little button on a website saying that it's accessible according to a certain (hyperlinked) standard - a bit like how you can find a Creative Commons button on a site and then understand certain things about the content's intended uses - but I can't remember the last time I came across it.
One thing that does occur to me is that with the number of 'silver surfers', the ageing population, medical advances etc., it should be obvious that the number of people surfing the web who may have some difficulty using it to the way it's built is only going to increase.