The highest denomination of coins in circulation in the Eurozone is 2€, higher denominations are collectibles only. The most common denomination used for shopping carts is 1€, though over the last decades, a lot of supermarkets have changed to systems allowing also 2€ and 0,50€. Especially the latter is hardly more of a motivator than $0.25 would be, so I don't think coin denominations are the main reason why cart coins are common in Europe but not in the US.

@Sabine I remembered a 10EUR coin, but now that I think of it it was probably a 10ILS coin (looks similar to 2EUR). But 1EUR is still more of an incentive than $0.25. Another reason may be the employee costs... at $7-8 minimum wage, Wallmart can have someone go around collecting carts. With the vast parking lots Americans have, no-one in their right mind would expect people to bring carts back to a single location, so they'd have to collect them anyway

Large parking lots sounds more probable to me :). Plus, I have only been to a US supermarket 3 or 4 times in my life, they have always been somewhere near the highway, where you wouldn't have been able to walk the cart anywhere, whereas supermarkets in Germany are often right next to a residential area, which might also be a reason. Btw, german supermarkets usually have some 5-10 "return points" for shopping carts, there's not one single location to return the carts to.

I've been to the US for so long the amount of parking space is barely noticeable anymore, but I still miss using coins....

In addition to US currency being a poor motivator to return the cart, there's another problem. Since $0.25 coins are so marginal in value, I don't carry them around with me. When I'm in public, I carry only paper money, and when I get change from a machine or clerk, it pretty exclusively goes straight into my glove box. If I encountered one of those coin shopping carts, I'd have to go back to my car and hope that I have the correct coin sitting in reserve somewhere.

@SilvioMayolo I had to beg for money the last time I first time I went to Aldi.

Even if the coin denomination is not enough of an incentive for shoppers to return their trolley, it will be for school children and home-less people. Not having to pay staff to collect the trolleys, will still save Aldi some money.

Where I used to live in Europe, some supermarkets that used 1 euro coins had a problem with the Polish Zloty coin, which has the same size but is worth a lot less. Some trolley locking systems require you to put a coin in the trolley in front of the trolley you want to unlock. If you return your trolley, you don't get your coin back but the one in the trolley you lock yours into. So, you might 'spend' 1 euro on your trolley and only get 1 Zloty back. The Aldi supermarket, in the town I used to live in, would exchange these Zloty coins for euro coins to keep their customers happy.

@littleadv Re "This is much more effective than a ... deposit against carts being stolen." As far as I understand, the motivation in the case of ALDI was not primarily theft prevention, but saving on labor to collect carts from the parking lot. ALDI is famous for thriving on a 1% profit margin, and numerous measures to keep costs low: In the olden days their cashiers had to memorize the price of every item sold in their stores (~ 1000 SKUs): no need for expensive scanners. Early stores did not even have a phone: store managers passed list of deliverables for next day to delivery drivers.

@njuffa if you watch the Tucker Carlson video, you'll see that he's talking about homeless people using the shopping carts

@SilvioMayolo, I always carry a quarter with me: it's hard to flip a coin without one.

@littleadv Who he? FWIW, the question does not mention "Tucker Carlson". I know ALDI from Germany in the 1980s, and chained shopping carts released by inserting a coin were not a thing back then. But by the time I visited Germany in the mid 1990s ALDI shopping carts had acquired the coin locks still in use today. I did not observe any homeless people pushing shopping carts there or abandoned shopping carts in various parts of town like I see in the Bay Area. Locking the carts was all about driving down cost, something ALDI excels at.

The coin value doesn't matter that much at all. Most folks I know carry a purpose made "shopping cart slug" that fits the coin slot in the shopping carts. These slugs range from a simple plastic disk the size of a common coin to a larger metal thing with a rectangular tab and a rounded part to go in the shopping cart slot along with a keyring attachment. Most such slugs are given away as advertising by various companies and organizations. The point of the "deposit" is to for people to put the carts back where they belong rather than to preven theft. 2€ is far less than a cart costs.

At a supermarket near me in the UK we have both £1 coin trolley deposits and wheels that lock if you try to walk out of the car park. The wheel locking system is also used on the sloping travellator that takes you and your trolley between the ground floor and the shopping floors. I carry cash but not many coins, but do try to keep a £1 coin in my wallet all the time

It's not a security deposit, in any real sense. The cost of a cart far exceeds the euros, even in the rare case where you actually use real money to put them in. It's more of a ceremonial thing, I suspect more people will "remember" to return their cart if there's a begin and end procedure to it. That said, in practice I still see abandoned carts occasionally in Germany; These are rarely "stolen" as in removed to keep them, but some (antisocial) people just use them to walk groceries back to their homes and just dump them somewhere nearby rather than walk them back.

The Albert Heijn in the Netherlands (or at least, my local one) has phased out the use of coin slots for the carts, and for years you could also get a plastic token from them, and even decades ago, supermarkets would hand out plastic or metal tokens (some with a keychain, with release mechanism for the token) to use instead of a coin. It has never be a real deterrent for theft, AFAIK, but primarily a minor motivator for people to put them back in the cart-line, and lock them, which IMHO only had real benefits when moving a long line of carts, and ensured you pulled out only one cart.

"the answers to both questions are yes, they do" That is incorrect and misleading. If the answer to a question is "extremely rarely" then the answer is not "yes".

@Fattie we have different definitions of "yes", I guess. Is it true that very few American supermarkets have conveyors? Yes, it is. "Extremely rarely" is not very different from "very few". Do American supermarkets have them? Yes, they do. "Extremely rarely" is a qualifier, not an answer to a question "do they"