Saw it happen to a guy going to phillipines. I can't remember the airline though. He then got refused with one of them fake onward flight tickets. He was flat broke too. No more money to buy an actual onward flight. I was thinking this may be the best thing to happen to him. Clearly henpecked he scrounged up enough money for a 1 way flight to get to the girl.
No, it's about the money, they get paid if you overstay. In fact the ring a "cha ching" bell as your leaving the overstay counter at the airport to rub it in.