There's no safeguard here. The smart contract is a red herring. Smart contracts cannot see or alter the real world, they have to trust that someone does that for them. In the example of the charging station, there's no safeguard that proves that the charging station will charge my car once I have deposited cash. You can analyse all the lines of the smart contract and the workings of the blockchain, but it is wasted effort: I have no way to know whether or not the charging station will ignore the blockchain's state.

I feel this is grasping at straws. If I'm running a series of charging stations, then I absolutely do want full control. And if I'm the customer, I can simply call Visa or MasterCard if the owner tries that shit.