I think this is more of a North American-centric meme. It’s pretty rare in North America to have to put a coin in to use a cart. I think Aldi is the only one I’ve seen do it in the US. Maybe Lidl and Trader Joe’s (owned by Aldi) did it at some point but I haven’t seen it there in years. Basically they’re all German brands operating in the US. Maxi in Quebec used to do it but the past few years when we’ve visited my wife’s parents the carts have been unlocked, although they still have the locks. None of the other stores there even have the locks. Even when we visited her family in France this year, though, it seemed inconsistent. Some stores used them but others didn’t.

What I found to be the biggest difference between North America and Europe was the cart returns themselves. In North America most stores have corrals throughout the parking lot, but throughout the day employees will go collect the carts and return them to the store entrance. In France they also had the corrals but they’re never returned to the store by an employee. Customers grab a cart from the corral near their car and bring it with them to use in the store. That kind of makes more sense, in that it reduces the work an employee must do.