In many areas, it would take a ton of work in the effort of making destinations closer to each other. Huge parking lots, setbacks, wide roads, and detached houses on their own quarter, or even eighth, of an acre lot make it so the choice between walking/bicycling and using a personal car is not much of a choice.
Public transportation is also not an option due to how inconvenient it is due to how infrequently it would run, and the cost of missed or missing buses/trains, which again, run infrequently due to lack of density of people.
Plus the separation of commercial zones and residential zones mean public transport is always going to one specific area, and so if you have any interest in traveling outside the central core, you are once again depending on a personal car.
Public transportation is also not an option due to how inconvenient it is due to how infrequently it would run, and the cost of missed or missing buses/trains, which again, run infrequently due to lack of density of people.
Plus the separation of commercial zones and residential zones mean public transport is always going to one specific area, and so if you have any interest in traveling outside the central core, you are once again depending on a personal car.