Back in the 60s-90s when I actuallly got paid for working, my jobs had me flying across the US and overseas. One of the first things I noticed at airport arrivals were machines that dispensed luggage carts. Drop in a couple quarters, and you could gather up your bags and cart them away.
One of the major players at this was an outfit called Smarte Carte, or smarty carty as we travelers used to say.
A Smarte Carte Dispenser
An interesting side anecdote: these cart dispensers were also available in the international arrivals area but I suspect that they didn’t make a profit as this area was still on the “air side” and thus there was no place to change francs or pounds or kroner into dollars, and very few travelers had US coins to pay for these not-so-smart carts. You had to clear customs before you would find a bank on the “ground side” of the fence.