This is entirely untrue.
In my state, for example, you must be at least 18 to purchase firearms generally and 21 to purchase handguns or semiautomatic rifles. Every sale has a mandatory criminal and medical background check. The transfer applications (state and ATF Form 4473) require listing your name, date of birth, address, declaration of citizenship, Social Security number, driver license number, etc. Firearms must be stored in "secure gun storage." They are not permitted on various types of school property or property being used by a school, public demonstrations, state capitol grounds, and so on. You can only discharge firearms in certain places. You must have a license to conceal one on your person. You cannot possess short-barreled shotguns or machine guns. You need special licensing for short-barreled rifles and suppressors. I'm excluding a bunch of stuff—mostly federal laws—but you get the point. Violating any of those laws is a gross misdemeanor or felony. Keep in mind I live in a state with relatively permissive firearms laws! The laws in plenty of other states are much more severe.
Purchasing, owning, and operating a vehicle is much more easier than purchasing, owning, or operating firearms.
* Age limits: There is a similar age limit to buy a gun as there is to drive a car
* Driver's license: Pretty much anyone with a pulse over the age of 16 can get a driver's license and it's nearly impossible to revoke permanently
* Insurance: The legally required insurance limits in some states is so low that it's effectively useless