Good thing you checked, that’s ridiculous. If I’d cut a dado for some mixed stock and found out some of them were 1 & 1/3 instead of 1 & 1/2, I’d be pissed.
But in reality, if you're looking for a perfect fit for construction lumber, you'd also better let it dry out for a week before measuring and fitting, cause it was probably 1.5" soaking wet from the yard, and shrank a bunch.
I made a work bench with oak 4x4s for legs and dado’d in pine 2x4s for the cross braces. Nice and sturdy with a good enough fit and no movement I noticed over the past 3 years.
There is a lot of manufacturing deviation with lumber. If you are that picky maybe you could try talking to one of the associates. They tend to know the best places to look and they may even help you measure.
Dimensional lumber has negligible variance in width/depth most of the time which is why it's called that. It's really the length that's a crapshoot. Gotta love when you buy a bunch of 10' planks and a couple are a few inches short