When hosts rent out their car through Drive lah and have accepted the booking (or have instant booking turned on), it is assumed to be available for the guest in good condition. For this system to work, guests need to have confidence that cart they will pick up is up to standards.
If the car is not in condition as can be expected, like e.g. right pressure of tires, working aircon, then the guest can decline picking up the car. This is obviously very inconvenient for the guest and could have been avoided.
For this reason we may charge the host in order to help compensate the guest for the inconvenience and for finding alternative transport ($40), besides the costs of the trip itself. These fees are passed on in full (minus the payment fee of 4%) to the guest to make up for the inconvenience.