I’m not sure what sort of corruption you feel like others don’t have. Municipal dealings, old boy networks, quid pro quo, all the sort of corruption we think of that are biggest in Finland others also have but they also have the sort of blatant corruption and bribery that we think of as “proper” corruption. Fight for the top spot can be tough and we are currently in #2 behind Denmark, so that’s one Nordic country that’s ahead of us on Corruption Perception Index. So we aren’t uniquely uncorrupted or something, just that we have less of it than most others.

Corruption Perception Index isn’t susceptible to “it’s legal so we rank higher” bias. What could affect is that if some practises aren’t seen as corruption, but imo that’s common for many other places too. “Quid pro quo/old boy networks aren’t corruption, it’s just friends helping each other out”, “this isn’t corruption, it just smoothes the process”, “I’m just showing appreciation, I don’t expect them to do anything for me” etc are common excuses elsewhere too. I’d say more blatant the everyday corruption is, easier it is to excuse and not see the small favours and such as corruption.

And I don’t think we truly believe there’s no corruption in Finland. As with the happiness ranking, Finns love nothing more than to rush into to say how full of corruption we are and make a case that we’re actually really corrupt (forgetting that the ranking doesn’t say we don’t have corruption but rather that we have less of it than most).