My home town now has one of the most expensive airports in the world, judging by the landing fees charged to airlines. I guess that's why they want to charge a couple of extra dollars to get a luggage cart. [see pic below]
In Calgary, which has a very nice airport, and approximately half the landing fees of Pearson, the carts are free. And present in abundance, both inside and outside the airport (see pic below).
In Toronto, you have to press down the handle all the time to keep the wheels from locking up. [This is deliberate ... some kind of runaway-cart-prevention-measure thing no doubt]. You can see people all over the airport having trouble keeping their carts moving. Calgary's carts roll when you push them, with no extra complications involved.
So what's the point here?
You can try to extract a few extra bucks from every little thing. Lots of businesses do it. And it can be a significant source of revenue.
It can also make people feel nickle-and-dimed. This practice can turn the rental of a cart into something done only grudgingly. A grudge purchase is not a strong customer experience position to be in, is it?
So if you are doing this, you should start asking yourself what gains you might make in loyalty by taking another route.
What would Susan do?
Someone's got to pay for that giant airport, and I suspect there's enough revenue there that it would be tough to convince anyone to let people use the carts without a charge.
An alternative would be to provide sponsorship opportunities for the carts. Hotels, local tour operators, local tourist attractions might all be willing to sponsor the carts. Or brands that stand for comfort and convenience, like TD Canada Trust.
I would ensure that the whole thing occurred within some design constraints so that it would feel clever, thoughtful and interesting for travellers, not noisy and commercial. Any good agency could handle that element with ease.
After all, an airport is the gateway to your city or your country. Do you really want people feeling irritated as soon as they get here? Poor things -- they had no idea they would need Canadian COINAGE just to use a luggage cart.