Thanks for the response. I too have always suspected that this happens, but this is the first time I have positive proof. I wonder though, whose rule it is?
I seem to recall that Lockerbie was the result of “bags with no passenger”, and I think that was when the rule was created, but maybe my memory fails me. BUT, in this very high alert status it surprises me that two large bags were happily left on a US to UK flight. The airline definitely knew the passenger was not on board.