Mainly because interest rates are lower. In the US the mortgage rate is ~7%, in at least some countries in northern Europe it is ~3%. And it used to be 1-2% recently. This however doesn't mean there aren't also a lot of inequality in Europe.
"Danish bank launches world’s first negative interest rate mortgage":
* https://www.theguardian.com/money/2019/aug/13/danish-bank-la...
The best period was last year when mortgages were already around 4% (because they’re driven by the free market and what was happening in the US) and on top of that you had negative interest on your bank account, because Danish National’s bank interest rate was negative, so banked passed off the costs to customers. The negative interest rate also didn’t help when the inflation was going up quite quickly.