So how will the business know they haven't been tampered or spent or private key written down?
Hmm. Good point.
Possible solution is to print some type of verification hash on it that includes the address and timestamp?
There are paper wallets currently people can print and use seals but I wouldn't accept them like fiat, you would need a way that they were printed and don't let the printer see the private key, which would be impossible. I just don't see a solution but it would be nice.