Ah, I took the person to mean our physical geography. Our urban geography is of course the reason for our car use: we've put policy into place so that cars are incentivized and other forms of transportation are disincentivized, with density being a cornerstone of that.

Density is one factor but the complete separation of commercial and residential zoning is also a huge factor.

In a lot of walkable cities the first floor of most buildings is often reserved for low impact commercial uses like shops or restaurants.

I am in a car dependent city (I need the car to go to work) but the fact that there are 3 stores in walking distance helps cut down on the voluntary car trips significantly. Even the weekly trip to a far away store takes 10 minutes at most by car.

Correct. Was talking about the sheer size of many countries in NA makes it a much different situation than many countries in Europe. Could've been much clearer so I apologize.

I don't see what the size of the country has much to do with how we get around in town.

No pedestrians or bicyclists die on I-95, and few motorists do to boot. The issue is with cars inside cities, not the space between them. Of course you get between cities with cars, long-distance busses/trains, and flying.

The size of the country (relative to the population) means that land is relatively cheap. That leads to relatively less dense cities (at least most of them).

Land isn't cheap if you have to maintain infrastructure around it. Exclusive single family zoning is a pure loss. Single family housing should exist but it should be reserved for those who really want/need it. It's not something everyone should have because it doesn't match people's real needs.

Sprawl isn't a natural result of a large country, nor is US land unbelievably cheap (it's all over the place, with some expensive peaks in some high-sprawl areas).

Belize and Norway are extremely low density overall in their countries: they have very different house prices, but neither has much sprawl.

Sprawl is a result of policy decisions.

I would say the bay area is a pretty good counter argument.