If you live in a state that has concealed-carry laws, then you are likely wrong about your comment that "the only time" you interact with people with guns.
Even in those states it's not that common for people to actually carry guns, at least in cities. I lived for years in Houston, and it was very uncommon, even among people who had the license, in part because it greatly restricts where you can legally go. You can't enter any establishments that sell alcohol, post offices, educational institutions, most hospitals, sporting events, etc. Private property owners can also exclude weapons by posting a notice at the entrance. So you have to be very careful about how to plan your day if you're carrying.
The firearms are concealed, sure, but you can still talk to people. :) I do know a reasonable number of people who have concealed-carry permits, and none of them carry a gun regularly, if they're telling the truth, because it's too much of a hassle and they don't normally feel a need to. They got the permit so they can, but it doesn't obligate them to actually do so. My guess (but it's a guess) extrapolating from that is that only a small fraction of permit holders actually carry at any given time. But it would be nice to have a more solid estimate, I agree. The number of permit holders itself is about 2% of the population, but I haven't found an estimate of the utilization rate.
DC and Maryland (where I work and live respectively) have the most restrictive concealed carry laws in the country, ones that are probably unconstitutional. Illinois, where I lived before that, was the last state to enact a concealed carry law, forced by a court order after I moved out.
Minnesota was second to last, I like to think that being slow to adopt the law also means that the aggregate rate of people carrying concealed weapons is lower, or will at least take longer to reach the levels of southern states.
This unfortunate piece of legislation set back federally-mandated interstate permit reciprocity untold amounts of time.
Why is it that drivers licenses, marriage licenses (both licenses to exercise privileges) covered under the full faith and credit clause, but CCW permits are not?
You can't kill people with a marriage license. Driving, although very dangerous, serves a purpose other than killing people. Although I'm not sure I agree with interstate reciprocity for driving licenses-- a Texan or southern California driver plopped onto a North Dakota road in the middle of winter sounds more dangerous to the public than him having a concealed gun.