Allowing people to put in-law units in their backyard seems like a good move in the short term (to increase supply), but also seems like it might cause problems

Allowing people to put in-law units in their backyard seems like a good move in the short term (to increase supply), but also seems like it might cause problems in the long term: NIMBYs are then _even more_ incentivized to prevent new housing because they're making a killing off the overpriced shipping container in their backyard.