First they deal with travel, which is a Constitutional Right (of course that’s a general right not a specific right travel by passenger airline, but still there is no constitutional right to “utilities”). To that end most passenger transportation services are public utilities and regulated as such.
Airlines for the most part operate on government owned property, a federal agency (TSA) does security checks on customers, a federal agency (FAA) regulates equipment/employees/operations, and undercover federal marshals often secure planes during travel.
Ironically CEOs from the airline industry have previously come out asking to be regulated as utilities specifically because competition makes the industry financially unviable. It is an industry that has received taxpayer bailouts.