How the hell did friendship become so transactional? Is this an American thing I don't know about?
I have never even for a single moment considered asking a house guest to pay for food. I get being broke - I've been absolutely broke - but then I wouldn't offer hospitality because I couldn't afford to offer it.
But in all the cultures I've ever lived in, I have never encountered this. When people have only a little, then the meal is just simpler.