Well, don't ya think that the possiblilty of selling heaters to the underworld is pretty good when you don't see the customer ?
Many state laws require background checks/waiting periods to purchase weapons.
I fully believe in the right to "Arms" however I would rather not participate in Arming the outlaws.
Whenever I sell a weapon, I make a record of the sale and the s/n
If the person is not known to me personally, I demand a drivers license and make full documentation.
I'd hate to have the Feds knock on my door wanting to know the whereabouts of a weapon used in a crime. Imagine if the crime was against a law enforcement officer or government official
Better safe than sorry