I don't have a coin ever because I never use cash. Requiring a coin deposit would just discourage me from getting a cart most days. If I regularly shopped there, maybe I'd consider putting one in my wallet or something to guarantee I have one, but I'd have to be sold on the place first.
Requiring a coin is a hardship, especially in a plastic-oriented culture.
If you go ask at the service desk they tend to give out special branded cart-coins for free, they come with a little quick disconnect hook for on your keychain.[0] It's still cheaper for the stores to do that than to hire a specific person to gather carts.
Requiring a coin is a hardship, especially in a plastic-oriented culture.