The damages from the shotguns are inconsistent

Shotguns are close quarters weapons.
Hitting a target on long range will decrease the damage.

A shotgun shell fires multiple pellets towards your target. The further away it is, the farther the pallets spread away from each other, the smaller the impact it will have on your target.

So if anything this game is more accurate than any.
In call of duty you can get shotgun kills by firing from across the map which is highly unrealistic.