People keep trying to compare cars and buying health insurance with gun ownership. There are points to be made, but let's look at the essential question of purchase.

Anyone can buy a car, even if that person will not be old enough to drive it on public roads for years. It is when, where and how that vehicle is operated (on roads owned by the government) that are suject to regulation.

With guns, it is the purchase that is regulated, controlled or completely banned is some jurisdictions. Not the same situation as with cars at all. To be equivalent, you would allow unlimited ownership of guns but restrict their use on public lands or in public places.

Insurance, regarding ObamaCare, it still different. Purchase is mandatory. Please show us a place in the US where owning a car in mandated by the government. There are a couple of tiny towns where gun ownership (and training) is mandatoty, but they have a "conscientious objector" clause that lets anyone who does not what to purchase a gun to "opt out".