I have a mechanical deadbolt with a keypad that can be opened by anyone with the right combination. It's handy when I'm not at home but need to let someone in.

For Airbnb, etc., you'd have to change the combination regularly (which is easily done in about 30 seconds) but at least I don't have to worry about getting locked out if I forget my phone, it's battery is drained, cell service is out, etc.