Here’s an interesting report on what might be called “accessibility backsliding”: http://informahealthcare.com/doi/abs/10.3109/17483100903387424. Apparently some universities improve their web accessibility at one point in time (often when they have external training and support), but then fall behind when the external support goes away or internal motivation fades, and when new technologies jeopardize access, unbeknowst to the developers.
Add to this a study of Greek public websites that seem to have declined in accessibility over a 4-year period, possibly due to having more inaccessible Flash and uncaptioned videos: http://www.springerlink.com/content/l23x52751j3v1557/?p=c1456fad679f4d79bf353d68ae78e12d&pi=5
and we may come to question any assumptions about continual progess. Accessibility tools are definitely improving, so it’s probably true that it’s easy to create sites with exemplary accessibility, and maybe there are more such sites than there used to be. But it may also be true that the continuum is stretching out in the other direction at the same time: there are more inaccessible sites than there used to be, and their number is growing faster.
(Of course, this all raises the question of what an “accessible site” is, but I’m going to leave that alone for now.)
What if we were to think of inaccessibility as analogous to an infectious epidemic? We have infectious agents — web technologies — that are both permeating the environment and rapidly mutating. We have populations, most of which are immune but some of which are susceptible to the inaccessible features. We have some individuals and organizations performing the role of medical researchers: identifying new jeopardies, developing diagnostic tests and clinical solution, and they are under-resourced. But we have almost no one scanning the entire environment from a “public health” perspective: how many new cases, what is the rate of cure of different treatments, etc.