It is also in the domestic contract of carriage when a flight is part of an international itinerary. Has anyone ever gotten pushback from an agent at LGA or JFK when asking for this?

RULE 150: APPLICATION OF FARES
A)
Where a local or joint fare is specifically published via the desired routing from point of origin to point of destination, such fare is applicable over such route.
Delta Domestic General Rules Tariff Page 24 of 51
B)
Unless otherwise provided, flights designated by class(es) of service (for example "First Class," "Coach," or by other classes), type of aircraft (jet or propeller) and flight departure or arrival time, as specified in connection with the application of fares, refer to flights bearing such designations and schedules, flight departure or arrival times, as set forth in the carrier's Official General Schedule.
C)
Fares and charges apply only to air transportation between the airports and/or heliports through which the cities named in connection with such fares and charges are served by the carrier or carriers by whom, or on whose behalf, such fares and charges are published. Ground transportation other than that specified below will be arranged by the passenger at his/her own expense.
EXCEPTION: Passengers making connection at LGA/EWR/JFK airports to/from international flights scheduled to depart no more than 6 hours after the scheduled arrival of the passenger's flight at LGA/EWR/JFK airports will be provided ground transportation between above mentioned airports under the following conditions:
1)
Such ground transportation will be provided without charge by independent contractors in the business of providing such ground transportation, upon request of the passenger.
2)
Where ticket coupons have been issued to cover the services of such contractors, and when such services have not been used, the coupons will have no refund value.
3)
Such independent contractors are not agents or servants of any carrier, and Delta does not assume responsibility for the ground transportation of