To each of those individual data points, I can give you counter-examples that do not support this theory.
It's actually extremely common for women to work. Usually a couple (with kids) works each 80% or some other kind of combination of %....
Don't spread misinformation, please.
Or maybe you were misunderstanding the situation?
Source: Am Swiss (lived large parts of my life abroad, but am back in Switzerland since 5 years)