Actually, it's some rules in a spreadsheet. You get tenants out of your rental because someone is getting paid to do it - their salary is in some spreadsheet - and then their work is verified by someone else who is also getting paid to do that. These complex systems of incentives are currently managed by humans.

You could setup a similar incentive system as smart contracts. If your tenant does not pay, you could get him evicted much fatser and automatically, because another smart contract can pay the enforcer. And the overall fees are subsidized and tradeable.

Of course we're far away from doing that and both approaches have pros and cons, but it's arguable that the "human-managed" approach is clearly superior.