AND it doesn't matter WHAT the other airport let you do because what they let you do has everything to do with THEIR policies and scanner capabilities and whatever CURRENT airport you're in follows a policy written with the equipment THEY have in mind.

Airport A lets you keep your laptop in the bag because their scanner is powerful enough to see through circuitboards and batteries to tell whether there's C4 or whatever wedged in there or not, airport B has a "laptops out of bags and power it on for me please" because the scanner in airport B can't see through all the semi-precious metals in the circuitboards and battery plates, but they're pretty sure you can't wedge enough C4 or whatever in there between the scan-blocking parts to do anything and still be able to turn the thing on.

But airport B does know what airport A does or has and it doesn't matter because they don't have it.

It's shitty and we should have standardized if we were going to do it all, but I'm betting some actuary somewhere has actual statistics on the semi-effectiveness of having differing policies and the confusion that sows.

On paper it's probably theoretically harder plan around a system you don't know, or something.