Interesting! Seems like this could very easily be generalized. Tool sharing/swapping, ditto for books, rides to things other than the airport, etc. E.g. on the latter: some medical procedures like colonoscopies (basically anything that involves general anaesthesia) require you to have someone pick you up at the end, you're not allowed to take a Lyft home. That seems highly viable for trading favors, though hard to build trust on unless it's part of a larger sharing network.