It can be difficult taking a layout that someone else designed and doing the code for it. Especially when they design it so it’s more like a magazine ad rather than a website.
It’s not the designer’s fault really…how can she know better if she has never done the actual coding? It makes the coder’s job much more difficult since they have to figure out how to take this “magazine ad” and make it into as much of an accessible website as they can. Or maybe it is the designer’s fault…if they’re designing for the web they should know at least the basics of XHTML, CSS, and accessiblity.