The whole "I pay this time you pay next time" is already covered by "everybody brings a case once in a while", but if the guys without cars just ask someone else to pay for it when it's their turn it won't add up.
If you're going to make assumptions, perhaps start with those that don't paint me in a bad light.
If this was a long time friend, I'd let it slide. It's just a case of beer, and in Germany beer is dirt cheap. If this was a new acquaintance, I'd let it slide and take note that it's not a person to make friends with.
> If you're going to make assumptions, perhaps start with those that don't paint me in a bad light.
Good point. But all of this isn't a problem of payment systems, but of people's behaviour.
I know many adults who believe that splitting bills is a normal and reasonable thing to do.
These are etiquette rules, which have their benefits. Since nobody is forced to follow etiquette, they help you to learn things about people.
Generosity is one of the easiest life hacks to find out who is friendly towards you and who is not. If you buy them a drink and they won't buy you a drink back, that's a tiny cost for you to know what kind of fellow you're dealing with. If they buy you a drink and then asks you to transfer money to them, you also learn something about them. If people splitting bills want to sit and count to make sure that everybody pays exactly for what they had, then you learn something. And so on.
If you invite people for dinner a few times, you will learn something about that person whether you wanted to or not.