The difference between theft and a trade is consent. "Rent is theft" doesn't make sense because renting from someone is consenting to their payment requirements for living on their justly acquired property. Taxation is theft because it is imposed regardless of manifested consent. https://steemit.com/anarchy/@thepholosopher/taxation-is-theft
RE: Taxation is Theft in all 1,896,967,245,998,098 Universes