this seems much more a theft of opportunity, than an orchestrated scam. it isn't hard to imagine someone thinking, "oh, i'll take these and see if i can find the owner, but if not, oh well, they are nice so i'll keep them."
at least in the US, you need a BP plus ID to get to the security checkpoint, and there is no real way to guarantee you'll be close to someone who has something worth stealing, or that you'll have the opportunity to steal it.