Actually Easton, it's the other way around. Since this is an RP game, thieves WILL happen. Do we really live in a world where there's no war or crime? No. Every day there may be a mugging on the streets or a hostage taken. Stop putting limitations on things, the world will never be perfect.
EDIT: About the labels, there shouldn't be any at all. They should just be able to steal without having a label or marking over their head. We don't see any labels above a pickpocket's head in real life, do we?