Why is it rude to cook at somebodys house?

Hmm, guess I grew up around a group of people that were different than the "norm". I had a couple of my friends parents come straight out and say "If you go hungry, it's your own fault. You know were the kitchen is.". Granted, I never just wandered into the kitchen to grab something to eat unless my friend was getting something also.

Anyway, like others said, if it becomes a problem I just buy or cheat in Always Welcome.