It's been on the back of tickets that I've bought. Or else it says that you can't bring bags in.
Hmmm, I don't know. I wonder how that applies to other situations like going to a ballgame or concert and having bags, purses, etc checked? I don't know that I've ever seen anything that says "we have the right..." when purchasing the ticket. But they seem to be able to do it. Would that be a case of "we suspect everybody of being a terrorist?". Why can't they say "we suspect everyone of shoplifting". I don't know that anything like probable cause applies to store owners. Do rules of "unreasonable search" apply outside of law-enforcement of gov't?