We don't. They are a failed paradigm. From the beginning, they were designed to morph into a national registration system. We fought that, but it has been inching forward, bit by bit.
We should shuck the whole system and start over. It is expensive and not cost effective. The only thing it accomplishes with regularity, is to deny people their Constitutional rights. Most denials are false positives.
Any man too dangerous to own a gun is a man too dangerous to walk free. If we stop letting violent criminals out of prison, they wouldn’t be able to ignore gun laws that say they can’t have them.