Shotgun turrets have a plethora of damage resistances but laser turrets get no such benefits which results in laser turrets being destroyed far more often than shotguns. The upgraded Advanced Beam Turret and Advanced Laser Turret (the one that deals explosion + laser) get both more health and the resistances afforded to shotgun turrets- making me assume the resistances themselves are intended as a baseline effect. For reference, I've lost 1400 some laser turrets versus 652 shotgun turrets so far in a 65-hour run versus Rampant (fixed) (yeah, I'm playing kinda slow..) and my defenses are quite literally split 50/50 for each turret type. Ammo has costed me 304,000 total resources so far while the laser turrets are at 243,000 with the above. Shotgun turrets, on the other hand, are thus only at 48,150. It doesn't quite feel right that I'm very nearly spending more replacing my turrets than I am feeding them ammo- though there may be an argument that it's a result of my defensive design but I digress. The main point is just that them not having resistance feels out of place given the pattern set by the other turrets and on the gameplay side it's also a little annoying.
Gun turrets also don't have any resistances, while Gun Turret MK2s do. This may suggest that the "basic" turrets are then intentionally without but it mostly means they die to splash when used as part of defenses, and for gun turrets especially their range means they have to be close up to the wall in order to even fire. Laser turrets at least can sit a bit further back but then spitters end up just plinking away outside of their range (and that's with me running 0.8x spitter range scaling in my rampant config).
