In a very upscale "tract home" I found only a handful of actual code violations. This is one of them.

Taken before the flooring was installed, the single receptacle was mounted in a standard flanged plastic box. While it may resemble some "real" floor boxes, it lacks any means to adjust for flooring thickness.
(I will try to get a pic when the finished floor is in place).

Also lacking will be the heavy-duty coverplate. I doubt the "standard" type will stand up to...being stood on(!).

- renosteinke