I have another reason why they're not driving.
They don't have kids.
When you have kids, you don't have 45 minutes to get from point A to point B.
When you have kids, you need the car to grocery shopping, even if it's around the corner because it's hard to haul twenty bags of groceries.
When you have kids, you dread bringing multiple children on the bus, especially with a fat stroller.
When they have kids, they will start driving.