In defense of the caterers, it is against most city food service ordinances to give this kind of food away. Food that is cooked and plated must either be eaten at the event or thrown out. There are too many problems with food spoilage to try to save it for anyone else. It is also likely their business liability insurance requires them to either serve it at the event it was made for or trash it.
When I was in food service, it was (and probably still is) against the law to, for lack of a better word, "reuse" the food.
Employees could get fired if they took leftovers at the end of the evening, the business couldn't take a chance legally.
Which was a real shame because we threw away a lot of very good food, and a lot of employees were poor people.