Oh interesting, didn't know Finland had a 3 year rule as well.Finland also has a rule similar to that. Denmark (including Faroe Islands and Greenland), Sweden, and Iceland are more relaxed: tax residence end when you leave.
Looking into it, it seems Finland's 3 year rule is less strict than Norway's. If you cut your ties with Finland you can stop being a Finnish tax resident straight away, but the burden is on you to show it to the tax authorities. Also, Finland has no 10 year of residence rule - if you are not a citizen, even if you have lived in Finland forever, you are out of the tax net when you move abroad.
"A permanent move from Finland usually changes person’s tax status in Finland and/or in the other country. According to Finnish legislation a resident national who leaves Finland permanently is considered to be resident in Finland until three years have elapsed from the end of the year in which he left the country. Tax residency can only end earlier if the taxpayer can produce evidence that he has not maintained substantial ties with Finland. In comparison, a person without Finnish nationality is considered to be non-resident immediately after moving permanently away from Finland."
Source: Moving abroad | Fiscales