Comment by direwolf20

Quite possibly, but that doesn't seem to be their concern for whatever reason. It's very unclear to me what the supposed threat profile is for those cases (perhaps they're concerned it might be easier to do sufficient damage higher up given that the Shard narrows floor by floor; who knows), but The Shard one strikes me as particularly "funny" given you gain access to more of the building by wandering in the entrance next door to the one where the scanners are.