ADA rules apply only in places that are specifically required to be ADA accessible.
I love the artwork that accompanies ADA discussions. The drawings, while taken directly from the CFR, fail to include the specific CFR note that these drawings are NOT part of the code, and are included simply for reference. There really is no such things as "ADA requires..." Rather, it is better to say something is required by the architect (or building department) based upon their understanding of how ADA rules would apply in a specific situation.
There's a reason for this vagueness. Many things you might do to accomodate a wheelchair would increase the hazards to a blind person (as an example, ramps increase the chance of a trip or fall).
For everywhere else, the NEC and building codes are pretty quiet on the issue of receptacle placement. Not only can they be at floor lever (I've seen them in the baseboard), they can be IN the floor. Can't get lower than that. Or, they can be nearly high enough to serve that wall-mount big-screen TV, and still count.
Receptacle placement, generally, is a design issue and not a code issue.