It's cultural.

I've read that German society, for example, is largely based on contracts between the family unit and the state. Sweden, as a contrast, is largely based on contracts between individuals and the state.

As an example, Germany treats a married couple as a fiscal unit, Sweden abolished joint taxation in the 70s. Swedish parental leave is allocated per individual, and is mostly non-transferable.

In a lot of ways, individualism is produced by state contract in Sweden.