MOCAŠ
MB Enthusiast
They have a perfectly viable way of doing that if they chose (e.g. entrance & exit barriers + ticket refunded in supermarket), but instead they choose to allow companies to "control" their car park by sending out speculative invoices
I think you've misunderstood. The car park isn't controlled by a system of invoices, they are just issued to customers that haven't paid for their parking. I'm not familiar with this particular car park, but it's fair to assume that the supermarket will have some form of pay and display or time-based system in operation. Having barriers is all well and good, but if some of the spaces are shared with the station car park, which is free for rail customers to use, then installing barriers probably isn't feasible. As mentioned, it comes down to whether the signage made it clear that the space used by the OP's wife belonged to the supermarket.