Of course these days you could have a Raspberry Pi in a corner of the laptop case and the rest of it filled with whatever contraband, and still present a "working" computer to the security screener.
Nobody would seriously claim that airport security is an effective way of stopping determined people. It is a deterrent that works to catch thoroughly stupid people and to make smart people dwell on the anxiety of getting caught.
Yep. I've never had to demonstrate that my devices are real at the security checkpoints getting into airports, I just put them in the trays and the X-ray scanners tell the agents that they're safe.
Now, dealing with the customs/pre-clearance checkpoints, that's another matter.
