Car is something where a regulation can be done effectively. Saying "each household has to have one" is a lot harder to implement. For cars there is a limited

Car is something where a regulation can be done effectively. Saying "each household has to have one" is a lot harder to implement. For cars there is a limited amount of manufacturers and imports can be checked, too. Also there are regular inspections for cars. And then there is a big density of cars, thus even for people who don't own a car it's likely there is a vehicle not far. Thus it is quite efficient place to regulate.