The person being visited pays. It's like in France: if you invite someone to go to dinner, you pay because YOU'RE the reason he is there. It's like inviting someone to your house, but expepcting them to bring his own food. Or pillows, blankets, and bed. Or toilet. It seems pointless and impolite.
Inviting someone to your house for, say, vacation is an attempt to free someone from whatever problems he has at home and it's helping him. With that, it's helping him both mentally (getting away from work, etc.) and financially. Expecting him to pay is saying, "I want to help you, but only a little," which, to me, is bullshit.
I don't know . . . I don't really understand rudeness and inconsideration anymore. I've grown up and realized being mean isn't cool. Isn't it sad that people allow themselves to think that way?
EDIT: PS I would never expect someone to pay for me if I was visiting a relative or friend, but I think it's universal that that's how it goes. I don't know. Nevermind. I feel retarded. I just like manners.