The numbering thing is quite common, and it's getting done in places it was not before. I assume it's to track stuff on camera as it goes through, so they can see for example bin C22 to see who loaded it, who put it on the belt, etc. It would not be all that hard for somebody to plan to sneak something through, let bin C22 go through, and fiddle around with jacket belt and shoes until the bin cleared, then go through inspection, or leave if they discovered a killer snow globe in it.

It would also help in thefts to see the same person put something in the bin and took it out, say $100 bills from tourists going home.