Currently Sweden is on a race to be first cashless society: many shops completely stopped accepting cash (many also started to use iZettle [1]), people usually simply don't carry cash with them, and if it happens that you need to send money to other person: Swish [2] is to the rescue, which is direct bank-to-bank money transfer system for small amounts.

On other hand everything is traceable, you can call tax office and ask who is get paid what, if you want to know where the person lives: just hitta.se them by name, you will also get avg income for household there.

- [1] https://www.izettle.com/ - [2] https://www.getswish.se/