Taxable income is public information in Sweden, and you can basically buy a catalog containing the previous years income for everyone in a given area if you'd like.
Stuff like addresses and so on is also public information in Sweden, for what it's worth. This always makes me feel a bit strange when hearing people considering releasing someone's address to be doxxing and something horrible - like you can just look up any person in Sweden, and the societal consequence is that literally nothing happens. Same with the incomes, nothing whatsoever happens from having this be public.
Actually addresses being public are causing issues. Sweden has a lot of problems with gang violence, and gang members often register their public addresses to other peoples addresses, causing innocent people to be killed. The address you enter is in no way being verified beyond it needing to be a valid address.
I have a very hard time believing that sales-people and trades-people don't take it into considering when negotiating or quoting a price. One of the reasons a car sales person wants to "check your credit" early in the process is to get your credit rating and address - which helps them guess your price sensitivity - and many home services certainly take into account the area you live in even when it is irrelevant.
Yeah, "checking your credit" doesn't exist, really, outside of the US. When making loan decisions, your income and loan totals/history are the main things considered, not an arbitrary score by private third parties that couldn't keep the data safe if their lives depended on it.
A credit score is determined by your loan totals/history.
Every lender needs to assess credit-worthiness in some way, and they resort to the very similar schemes, with minor procedural differences based on cultural factors and historical accident.
Except that credit scores in the US include things such as evictions and credit card use, scores going down if you repay a loan in full and other bullshit, which a random bank determining your credit worthiness in France doesn't do. They ask for proof of income, check with Banque de France if you have outstanding debts or if you have failed debt payments, and that's it.
Of course there's no requirement, but everyone knows that paying off a loan early can, in some circumstances[0], lower your credit score. Nobody is taking the time to look into your score and see why it was 810 last month and is 780 this month. They just use the 780 and move on, so it can absolutely affect the rate you get, and whether you get approved or not. No creditor is overriding a denial because they spent time investigating your recent score change.
[0] Usually the credit score is a measure of how likely you are to hold credit over time. It is not a "how good are you with money" or "how much money do you have" score, it is a "how likely are you to pay this back under the agreed-upon terms" score. Part of that score is the mix of different credit types, so if you pay off your final installment loan (e.g. car, house, private loan, student loan), your mix of credit types just went from N to N-1, hence a temporary, minimal drop. This is also why paying something off early can negatively affect it (in certain models, but I don't think this happens much anymore). This is always used by people to explain how credit scores are stupid and evil and idiotic and evil and stupid, but its effect is always overblown, and your score almost always rebounds within a few months.
A lender or seller does not have to use any specific credit score. Many businesses calculate their own credit score based on borrowing/repayment history, and some do not calculate a score at all.
Incidentally, Norway appears among the countries with the lowest perception of corruption in the world: #4 among 180 countries (0). It would be interesting to look if there is any correlation with other countries where income records are publicly available.
Salaries are not the entire income. Corruption is usually some income in addition to a salary, but it may still be reflected in the tax record (that is, it's usually some service, board position, etc, not a suitcase full if cash).
Thus public tax records give a better transparency picture than salary records.
But you can't look it up anonymously. You have to authenticate with your national ID number, and the person will be notified about who looked up their income.
