From a distance, this doesn't seem like a particularly severe way to punish someone for parking that far outside the lines in a car park. Someone's pushed a shopping cart up to the driver's door to make a point, but that's it. Only it isn't. When the driver eventually got closer, they would have realized that what at first appeared to be a mild inconvenience is now a much bigger problem.
Some enterprising revenge genius has attached the cart to the door handle with a cable tie, and we all know how difficult those things can be to get off when they don't want to budge! Nine times out of ten your bare hands won't be enough, so unless the driver had a knife or a pair of scissors on their person, they'd have been helpless. The best thing to do would be to go back into the store, and purchase something capable of cutting your way to freedom - and then never parking like a fool again.