For the first part, yes that will vary place to place. That's why I said "often", but it's a viable method in quite a large number of locations. Especially in those which are currently some of the worst places for walkabilty/biking/public transit at the moment. Places with narrow streets are generally speaking more walkable to begin with. There are still other ways to make improvements anyhow

For the second, I am also talking about the quantity of roads (the more places part). More car centric places are going to have more roads to maintain in general.

But it's still worth mentioning that car centric design can still can lead to trucks being used in places where there are viable transportation methods like trains (this applies more so for longer distances than just delivery to houses but a number of cities do have highways that run through them).