In the U.K. people are indoctrinated from birth to believe that you work hard to save your money to buy a house and the value goes up so that you can retire with a valuable asset. Flooding the country with new property would completely upend that foundational part of U.K. culture.
If the governments of European countries wanted more property to be built, they could make it happen. The problem is, there is no appetite, they're walking a very fine line: more property must be built but property values cannot go down.
China is an extreme example (and has quality issues) but they have been building more than 10 million new homes per year for a long time, and now have tens of million of vacant homes that nobody wants to buy. That's a nightmare outcome for most Europeans who plan to retire on the value of their home.
The U.S. is fairly unique among western economies in that investing in the stock market has been a normal part of wealth building for the hoi polloi and while homes are important assets, they're not everything. In Europe, investing in the stock market is still novel, property is still the asset.