Except for people on minimum wage, I don't agree that those really count as wage theft.

Say you forced employers to account for the time closing and locking the store or to compensate people for spending hours away from their family. What would happen is that the hourly salary would drop to account for that, since in reality the workers are already taking those into account (as you say, they already consider it normal - and therefore expect it) when they accept the job.

Except for minimum wage workers, they are just examples where the actual contract is an informal agreement, and not the piece of paper that was signed.