I don't even see salary or what your debt is as "personal information" (am Swede not in Sweden), personal information is stuff that no one else would need to know. What people earn affects not just people around you and others in the workplace but also society at large, makes a ton of sense for that stuff to be public.
Especially great that you can see what employees at competitors earn, what your peers at your workplace earn and what your boss earns. Become a hell of lot easier to ensure you're not exploited. Helps that Sweden has a really strong union-culture as well.