that’s one of the common excuses that the mills quote. It’s bullshit of course, but it sounds plausible so they continue to get away with it.

Another bullshit excuse is that they’re providing an additional service by milling and planing the lumber for you, and that the nominal measurement is before that process.

It’s all just greed. If they could get away with selling a 2x4 that was half an inch thick, they would. At least it’s all standardized now.