Hey, thanks for this! While watching the Tour de France my friend and I were wondering if most people in France lived in apartments or detached homes. You have neatly answered our question!
France has endless suburbs. The contrast with Spain is quite stark. Suddenly most people live in town and village centres and they usually stop at the old historical borders.
In large cities, sure, but mostly out of necessity. Historically, the communist regimes there sort of forced industrialization on people. Workforce was needed so they moved people from the countryside into flats, close to the workplace. As the change was mostly sudden, it was a bit of a culture shock due to people suddenly moving from their own house with a yard into a wee matchbox and not really adjusting behaviour to the new circumstances. So the apartment building culture in such places is quite different from the western one (in terms, for instance, of being respectful of your neighbour - like not drilling on Sunday at 8 am because that's when the quiet time - according to the law - ends).
So the drive there is to get your own house away from hundreds of neighbours as soon as you have the means, even if it implies commuting in hellish traffic.
Coincidentally, also why you might see some pushback from those places when people suggest walkable cities with apartment blocks. Because when suggesting that, everyone thinks Sweden or Denmark, not Eastern Europe.
Absolutely not surprised about Spain being top in flats after learning its interior, excluding Madrid, is basically the most sparsely populated region in Europe.