|A $190 find at the local gunshop|
In terms of "shootability" a shotgun falls between a handgun and AR-15, meaning a handgun is the most difficult to shoot well, AR-15 the easiest, and the shotgun falls somewhere in the middle. It is significantly easier to shoot than a handgun, but harder than an AR-15 because of the recoil and required manipulation. I know a lot of former and current military guys who can out shoot me all day long with an AR-15 but struggle with shotguns even though they have training on the platform. I know some SWAT veterans who love the shotgun because they are the old school kind of guys, but they still shoot an AR-15 better. I know some novice shooters who have picked up an AR-15 for the first time and been straight up good, and not quite so good with a shotgun.
On the other side of the coin, I know some average pistol shooters with near zero training on the shotgun who have picked one up and made shots they could never make with a pistol. I am at heart a pistol shooter, but in all honesty most people I know who own handguns are not. They are for whatever reason not willing to put the time and money into learning how to run a handgun to its potential. Nor would they be willing be put the time and money into learning how to run any firearm to its potential, but given the same amout of training most people will end up being more capable with a shotgun than they could be with a pistol. A shotgun is just easier to shoot than a pistol, and significantly cheaper to buy and run than an AR-15. That is why.