Should I charge for having to return a house key to the owner?

Tell the owner that they will need to come up with an alternative, like leaving the key in a hidden location or giving it to a neighbor. Be more assertive since there is no way to add on a fee now. In the future, you should advise people to get lockboxes for the key which would ensure you don't have to make an additional trip.

For tasks requested after booking is finalized, such as feeding snake which they communicated wasn’t needed and later asking after you were there, it’s completely appropriate to either say no, that wasn’t agreed to and part of services booked Or that you’ll modify the booking with a cost adjustment for the additional service -that can only be processed if the booking hasn’t ended, and support can help if you need help with modification.

For key return, it’s best to discuss before booking. Since it’s the security of someone else’s home (not mine), I ask them to tell me what they’re comfortable with (which puts any liability of that decision completely on them). Many possibilities exist, such as: lock key inside home when finally leave, enter/ leave through garage code entry pad, leave key under mat/rock/landscaping/ lock box etc., hand key to neighbor/ friend/ relative, mail key in a standard envelope,