I may buy one if it works. It would pay for itself in about 3 years. Parking where I am at is about $50 a day. If this thing can drop me off and go make me money it is a no brainer.
Does the pay off calculation include the frequent interior cleaning any rental car will need to be kept in service 24/7? Both normal wear and tear and spills, vomit, blood, etc that users are motivated by fees to pretend they didn't do until the next user or two after them reports it.
Skeptical it will work as advertised, though.