456 Berea Street and the Standard Guy have a very interesting post about the usability of accessibility evaluation tools. In fact accessibility tools and methods are very complicated something that doesn't encourage developers and designers to use it very frequently. In addition to the fact that most accessibility checking points can't be done via automated methods, checking one by one the different points is really a hard and difficult task and could be source of errors.

Accessibility has as much to do with usability than being purely technically correct. The site needs to have clear navigation, the ability to skip content areas, offer alternative layouts and be written in an easily understood style by the anticipated audience. Can an expensive evaluation tool be justified and are site-wide checks using such a tool actually required (rather than just for a “feel good” factor of control over the situation) post-production?

The point is that accessibility isn't the very important issue for many developer and designer, while it should be integrated in the core of website development especially for e-government websites and public services. And since accessibility is still "useless" only for a small part of internet users, people don't worry too much about the different checkpoints, let's say if HTML valid, color are visible enough, the website might be considered as accessible at a certain level.

Such issue will be important when all accessibility checkpoints could be automated and also the fix for the different detected issues. When you have 70 accessibility problem to fix in a page, better to be prompted for possible solution and directly correct the problem. Otherwise we'll be back to the usability issue of accessibility evaluation tools.