@James Hamling
Happen to be doing a lot of travel in Europe the last 3 years. My son is based in Sicily, brother near Lucca, Italy; trips to France, Spain, Germany, Hungary, Austria, others.
Currently meeting family in Malta for Xmas.
Not an all encompassing answer to your Europe vs US housing question.
1. Germany where my wife is from. They just kept adding an extra house unit to the end of the building.
2. Old towns and cities have narrow roads and streets due to horse drawn carts. Also to reduce sun from heating buildings and for shade. This restricted traffic forcing MFH in town.
3. Spain where we were at you couldn’t build out in the country side unless you owned a lot of ground. Prevent urban sprawl from taking limited farm ground.
4. Europe got blown up twice. Easier to add mass transit.
5. They moved to mass transit.
US has far more ground per capita. Cost less to do urban sprawl than high rise. Plus the US is based on forty acres and a mule approach to growth. The auto is a given right in the U.S. .
Basically if we followed part of the European model.
No more urban sprawl thru zoning.
Heavy investment in mass transit.
Tax autos out of existence.
Do away with parking in town. Europe did this out of necessity versus planned.