This might perhaps be true in the land of XXL everything, but in the space it takes to have 3 cashiers you can easily install 2 rows of 4 self checkout machines, and in Europe space tends to be more scarce.
They are a massive space saver, and when that's the space you have, 8 self-checkouts and a cashier have more throughput than 4 cashiers (which don't even tend to be staffed all at once).
You can always slur your words and say something like "Kisten" quickly. As a non native English speaker I do this sort of thing more often than I'd like to admit, you get away with a surprising amount even when you've spoken the language for over 25 years. 😅