Inter-city shuttles ... including airport shuttles ... are unregulated in Arizona. No state agency issues permits for such companies to operate. Inter-city airport shuttles usually must have a permit from the airport authority to pick up and drop off paying passengers at curbside. However, airport authorities do not handle consumer complaints against airport shuttles. Arizona's Motor Carrier Division oversees vehicle equipment, safety and commercial driver licensing requirements. It does not handle consumer complaints about service or cost. Fares, schedules, and customer service issues are regulated solely by the marketplace, competition and consumer choices.
If you book a round-trip with an inter-city airport shuttle, insist on a receipt that shows amount paid. It should also list departure time, as well as return pick-up time. Pay by credit card, if possible, so that you can dispute the charge if service is not provided as promised.