I feel so uneasy using my card when eating out in America vs Europe.
(everyone signing for card payments did also seemed weird at the time as, while there was no contactless back then, we'd been 100% chip-and-pin in Europe for some time, but I think that was a more well-known oddity of the US)
Is there actually any (pre-)authorization going on? My impression is as long as they have your card number, they can charge you whenever they want, the only deterrence being not committing fraud. Once I dined at a local restaurant (in the U.S.) and only realized I forgot to bring my wallet after the meal. I wrote down my credit card number and that was it.
For those who don’t know, in the US it works like this: a paper receipt is brought, which you write a tip amount on in pen and then sign. The total is then manually entered into the computer later on. Absolutely medieval technology.
It varies significantly depending on which European country you are talking about (we have massive social variations across our 30 or so countries), and then on factors within each country, down to the policy of specific pubs/restaurants and pub/restaurant chains.
In the UK, I've seen at least two specific cases (I don't eat out very much, even before the pandemic). These are: the waiter hands you a device where you can enter a tip as an amount or just click through to the final payment, OR the waiter themselves enters the final amount - without a tip - and then just hands you the device to press 'OK'. They will add a tip if you ask them in time. I haven't signed a card receipt for years.