Guns are pretty heavily regulated in the US though? Many kinds you can't buy at all, and those you can require background checks. (A lot of people seem to think that there are fewer restrictions on guns than there actually are, and that's before you bring individual states into the equation)
It's just everywhere else is even more outrageously restricted, which makes the US look liberal in comparison...
But to call guns unregulated in the states is to say that cars (among many other things) are completely unregulated too.
Guns are most certainly regulated in the US and quite heavily.
You can’t make a gun to sell without an ATF license. All guns must have serials numbers and customers pre-screened.
And that’s just federal law. Many states have even greater regulations.
A completely black market for guns would lead to things that could blow up in your hand or explode at any time, the same as unregulated drugs