Used to be commonplace for large shops (bookshops most of all, for some reason), to ask you to leave bags or backpacks at the desk. And if you didn't they'd sometimes ask to go through your bag when you left. Really kind of irritating.
Got to the point where I'd voluntarily offer to do so before they asked. Then on one occasion, at a large book store, found the desk staff reacting with alarm at my offer, apparently - as they explicitly said - because there had been an IRA bombing campaign in the area recently and they were scared I might have a bomb in the bag! I think their reasoning was if so they'd rather I left it somewhere other than the desk, and only blew up customers rather than them.