I think they had already paid something for the box and he was holding that money hostage. Something like extortion. You can’t have your money back and he won’t take the strawberries he claims are in excess of those paid for back. I would have definitely found a fair solution and forced it upon him.
It especially bothers me because this “pick your own” is supposed to be somewhat of a charming experience. It also sounds like the group of host and tourist guest(s), consists of ethnic minorities. I wonder if this guy is targeting them thinking they won’t fight back.
I know it would not have happened to me. I would want to be sure he didn’t say the box could be filled level or something like that and then it was heaped excessively. It doesn’t sound like that happened? Did you guys try to stack the strawberries 10 feet high?