Thank you for your honest answers. This question has been in the back of my mind since I first read about it some time ago, and when I saw it here again, I thought „Whom to ask if not these lovely people here?“ :)
It‘s quite interesting to see that it‘s not as uncommon as I thought.
Maybe it‘s because I am from the one country in Europe where the people are always „cold“ and „reserved“? Here you don‘t even get a Thank you when carry someone‘s groceries for three miles :D.