I think the research tested something slightly different than your experience, but not necessarily in tension with it

That may be the case.

The same moms you reference who are predisposed to find you a danger to your kids will react with horror if another mom doesn't live up to their standards of perfection.

That isn't what I usually observed. I could be next to a mom who's letting her kid stand up in the kid seat of the shopping cart, when mine was sitting and I had a hand on her to be sure she wasn't in danger when I was looking at the shelf, and most the scowling was in my direction.

As another pointed out, that's anecdotal. However, me and the other fathers would talk about this at gatherings, how moms kept a scornful eye on us a lot, but seemed to ignore other moms. Oh well.