leftovers

Why, when you order Chinese food or you get a doggy bag from a restaurant, do they give you the food in a metal or foil container??  Don’t they realize that 99% of the time you are going to reheat that food in a microwave?  Wouldn’t it be just as easy for them to put it in plastic or styrafoam and save us the trouble of having to transfer it to a dish and then wash that?  I mean, come on, it seems like somebody in the food service industry should have thought of this by now.