[simlan]

Good point. Think of the device as a lock pick for Aldi carts you can remove it and don't need to leave your keychain.

[gcbirzan]

It's not a lock pick for the carts, you need to leave it in.

[frm88]

There are some that you don't have to leave in the slot - they got quite widespread a few years back https://www.printables.com/model/430247-shopping-cart-coin-s...