Wait... car mechanics too? If you’re already billed for human labor cost on your invoice, what percentage do you tip on top of that? How is it shared between employees of the shop?

I have lived all over the US and have never tipped a car mechanic or heard of someone doing so.

Assuming you go to the same garage, and that the mechs are not the owners... Your car is one of many at the garage. You may have particular expectations on time or how you like your settings (specific wheel alignment, etc) A bit of extra "appreciation" means your car may get fixed earlier, and come back with a few extra things adjusted without being on the bill, along with extra care to meet your specific asks.

Or so I was told. I saw it more when I was younger than I do today.

And somehow I get that in the rest of the world by just being a regular customer, without paying a tip.

I've never tipped a car mechanic. They bill their labor rates anyways, tipping in such circumstance should never be expected.

Generally, most tipping is at restaurants and bars/pubs. Hairdresses/barbers/salons is also very common because of the close personal interaction with the worker.

Most of the time you tip at businesses that would be expected to employ low-education, or poorer or immigrant workers (and by extension, more easily abused workers.) Restaurants, salons, car washes, etc, all tend to employ poorer, less educated people, and also tend to be highly tip-based businesses. So for the most part you're expected to tip at businesses that traditionally abuse and underpay their employees.

I’ve had great relationships with independent shops and only tip when they do something quick and don’t charge.

It seems weird that USA is in general more expensive than europe if this is the case.

Yeah. Like why can I get a draft beer anywhere in Amsterdam for 3 euros MAX 4. At the top of the 5 star Okura hotel, beers are 4/5 euro. Of course, fancy beers can be 6 euros.

But in the USA, it is not uncommon to see Budlight selling for 8 dollars or more. (don't forget to tip!)

Yes I noticed the same thing, but only in the cities. Cost of living there is generally higher and income is as well. If you go to a small town in the US a beer can be 3 dollars and a coffee 1.50 or so.

If they weren't using the same currency there would probably be difference in inflation due to very different economics between let's say New York and some tiny rural village.

In the US it is also customary to NOT tip if the person performing the service is the business owner. Eg at a hair salon or similar.

Hairdressers and car mechanics? Really? :o

I've never tipped my mechanic, but I absolutely tip my hairdresser. I suppose it depends on the place, though.

>car mechanics

Really? I never know anyone doing this