I checked my website (http://www.huffmanlegal.com/) and found these errors:
Report resume
Priority 1 Priority 2 Priority 3
Errors 2 0 1
Warnings 16 19 21
I was amazed that my site has 2 priority 1 errors and 16 warnings but I guess I never thought enough about accessibility when I created my site. I used commercial software to design my page based on a template. Apparently the original template designer did not concern themselves with W3C/WAI or accessibility in general. I suspect many pages have similar problems.
My sister-in-law was an executive director for a non-profit that specialized in helping people design accessible web sites and use technology that allows them to live productive lives. It amazes me when I read all the accessibility issues that a web designer needs to consider when creating a fully-accessible page.
But the work pays off! Accessibility means equality. People who could not fully appreciate and use your site can not get far more out of it. They can see the text better or have the images read to them so they can see what they are missing or they can navigate around the site better if elements for assistive technologies are integrated better into the site framework.