Actually, it varies depending on where you live/where you go here.  Every Aldi I've ever been to has the coin system, the Walmarts around me have wheel locks with an invisible fence (hardly an honor system) and Publix has nothing.  Honestly, I prefer the coin system, because people in the Orlando area are fucking lazy, and if you don't make them put their carts back they leave them sitting wherever they got done with them in the parking lot.