system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why is it the USA doesn't have a national gun license?

I thought this to my self and looked, but didn't find an awnser on reddit. Anyway, there wouldn't be any state laws on the matter but instead, we could have congress conduct laws on this.

Other than that would it work or not?
gpt
One legal answer among many:  The Constitution only empowers to federal government to act in specific ways.  Any power the federal government is not specifically granted by the constitution is delegated to the states.  A national gun license is not one of those powers, so the federal government cannot create one.  

There exist various legal loopholes the federal government has used to expand its powers beyond what you would expect, but that is an altogether different discussion.

The political answer is:  The NRA is a very powerful and wealthy lobby, and it is opposed to any increase in restrictions on gun ownership.  Especially the idea of a national gun license.

The Ideological answer is:  If you have a national license, you now have a national registration.  If you have a national registration, you now know exactly whose doors to break down in the event the government wants to confiscate all the guns in the nation.  While no-one believes it is possible *for the current government* to do this, they are afraid of what might happen 10, 20, or 50 years down the line, in a vastly different political climate.  It was only a about 70 years ago that we were locking up people of Japanese ancestry en masse, for example.