But you can nicely check your items and say “ope looks like one of the fries got missed” and not make a big stink about it
That’s true, but I don’t know how much of a stink was made. If someone is unbagging everything at the counter, they’ve probably been burned before, so I can see some reason to take a harsh tone – enough to show they’re tired of the BS. If, instead, they started throwing things and screaming obscenities, yeah, that’d be an overreaction.