I think you guys keep stealing carts, so they have to keep them under lock and key is all...
I do agree that if you are going to a store, and you know they have the quarter operated carts, bring a quarter. Its like leaving your wallet at home.... But I bet enough people complained about them, and they are higher maintenance and cost, than regular carts, so they did away with them. Plus the one store I'm thinking of was located in its own parking lot that wasn't walking accessible really, so they don't need to worry about hobos walking off with them.