European cities that are not Paris do indeed have some density issues. It's nothing like the North American shit show, of course, but it still shows an issue.

Fine if you want to keep your historic downtown, but you should build a modern dense "La Défense".

UK fails, Anglosphere housing shortage issues too. London is not dense enough and has no strong CBD proportional to its size.

Germany fails, as Berlin should be bigger than Paris if it weren't for WWII and the division. Germany is full of bad austerity and the "polycentricity" is simply a failure to catch up after development was interrupted. (Consider if they properly developed Berlin maybe there would be fewer AFD issues in the former East.)

Not sure what the situation is with Milan.