Earlier quoted context omitted.
> I assume such situations occur often in Sweden where it's really awkward if you want to hang out with a crowd from lower social class because they know your earnings. You don't have to be in Sweden to have a pretty good idea within a few minutes of talking to someone, of what the ballpark for their earnings is. Your social class is written all over your face, your clothes, your manners, your manner of speaking, the…
I am technically in the upper class based on income and place of residence. I drive an 11 year old vehicle, wear inexpensive clothes (often plain tees), eat out infrequently, etc. I unintentionally spend more in areas that tend not to be obvious to non-friends. I'd be upset if people could easily lookup my income.
But yes, it's possible you are sufficiently outside the grain that you don't have any obvious tells about your social class. And, of course, a dedicated confidence man could fake enough of them to fool enough people enough of the time.
But that would be the exception that would prove the rule. And even if they were publicly available, you have to be deeply pathological to be looking up the tax records of your acquaintances, I can't expect that to be a regular problem in Sweden.