There really isn’t a general rule to availability of such transfers but airlines seem to reserve the right to provide it if they deem it fit to do so.
For example:
Rule 17 Ground Transfer Service
UA may provide or procure ground transfer service between airports and city centers, between airports and any point in a Passenger’s itinerary, or to places of lodging.
Except where ground transfer service is directly operated by UA, it is agreed that any such service is performed by independent operators. Such independent operators are not agents or servants of UA, and UA assumes no responsibility for the ground transfer of any passenger and/or his/her baggage. Anything done by an employee, agent or representative of UA in assisting the Passenger to make arrangements for such independent ground transfer service shall in no way make UA liable for the acts or omissions of such independent operator.
In cases where UA maintains and directly operates local transfer services for its Passengers, the terms, conditions, rules and regulations of UA, including but not limited to, those stated or to which reference is made in UA’s Tickets, Baggage Checks and baggage valuation agreements shall be deemed applicable to such local ground transfer services. No portion of the air transportation fare shall be refundable in the event local ground services are not used by the Passenger.
While USAir/AA provide no such mention at all for either "Online" or "Interline transfers".
Southwest states explicitly that it would be at their discretion on whether or not to provide it:
c. Ground Transportation
(1) Unless provided at the direction of Carrier, Carrier does not assume responsibility for the ground transportation of any Passenger or his Baggage between any airport used by Carrier and any other location. Ground Transportation is at the Passenger’s expense.
So you would need to check with individual carriers that you fly in places where multi-airport connections are possible.
Credit:stackoverflow.com‘
4 Mar, 2024
5 Mar, 2024