>That's because population density in France is 4x higher than that in the US.

That's a meaningless statement unless you're comparing the Paris metropolitan area to some similar area in the US. France doesn't have a sparsely populated continental interior to drag down the nation wide population density.

Depends on what you compare it with. Compared with Netherland, rural France is very sparsely populated.

But even in rural Netherland (it exists!) you need a car. We're really talking about cities here. In a well-designed city, you shouldn't need a car unless you need to go to a rural area outside the city.

That assumes a value judgment about what is a “well designed city.” Sprawling car dependent cities offend my personal aesthetic sensibilities, but there is a reason that the biggest internal migration trend in the US is away from cities like New York and to cities like Houston and Phoenix. Being able to easily drive everywhere can be very convenient.

But I think it's unhealthy if it comes at the cost of not being able to walk or bike anywhere. Kids need to be able to get around on their own, as should poor people who might not have a car. Cars have a tendency to clog up city centers, and their main value is outside cities, so designing a city so that cars are mainly for getting out of the city, while most places are easily accessible on foot or by bike, I think that creates a healthier, more fun, and more integrated city.

I admit for me personally it's mostly aesthetics, but this is also the direction that many professional city planners are working towards. At least in Netherland. It wasn't always like that; the 60s and 70s were very car-oriented, until people started to realise what the impact of cars on living spaces was.