They're truly all over the shop, my boss tested 'positive' on a RAT test three times before boarding their flight to site - PCR negative back each time, just a real stuff around tbh (guess who gets to do the work while they have to go isolate pending results).....they really, really aren't. So much so that the government lab I work at has basically told us that they're one of the least reliable tests around and to always get a PCR unless the RAT comes back positive.
I get why use them because good enough is better than nothing, but they're certainly not reliable that's for sure.