I can tell you this is illegal in europe!(you can not sell an item to a lower price than the marchant price) it 's called illegal competition("concurrence deloyale" in french), so why airlines use this system with their P2F schemes? why airlines don't understand the danger of these practices.
Maybe in Euro-land this is possibly illegal, but in the UK it is not and often supermarkets have so called 'loss leaders' to attract punters in the hope they stay and buy some normally price stuffed.