[jq-r]

The "coin" part is usually detachable, so no need to leave the whole set of keys with the cart during shopping.

[gcbirzan]

Yes, but they do cost money and effort to get. A 25-50 eurocent coin is probably equivalent.

The only thing that's useful about those things is that it's easier to get them faster.

[1718627440]

Where I live it is always 1€ coins.

[ceejayoz]

But leaving it on is a good way to avoid forgetting to it.

[hananova]

There’s ones with a “notch” in the coin part. So you unlock the cart, twist it, pull it out.