The tax you pay is public record.
For example, in Sweden, you can get a 'tax calendar' (a bit like an old-fashioned phonebook, but with total pay instead of phone numbers). You can buy relevant pages conveniently online.
https://en.wikipedia.org/wiki/Taxeringskalendern
It is a trivial division-by-twelve to determine the salary of your co-workers and neighbours.
The tax you pay is public record.
For example, in Sweden, you can get a 'tax calendar' (a bit like an old-fashioned phonebook, but with total pay instead of phone numbers). You can buy relevant pages conveniently online.
https://en.wikipedia.org/wiki/Taxeringskalendern
It is a trivial division-by-twelve to determine the salary of your co-workers and neighbours.