Look at the M1 and M14 rifles. The firing pin isn't an inertial type, and there's no spring to oppose it. Eject a fresh round that's chambered during normal cycling, and you'll see a tiny dent from the firing pin every time...yet they don't slam fire on any sort of consistent basis...even with soft commercial primers.
The Garand slamfired enough that the military replaced the rare round firing pin with a lighter "scalloped" version around 1942. The Italians added a firing pin spring on their box magazine versions.
All to reduce the weight and kinetic energy of the rebounding firing pin.
Notice how many rounds the guy with this Tavor fires. If he had a mechanical problem he would have recurring slamfires, but he did not. When you see the slamfire, notice that the finger is not on the trigger. He was running Federal American Eagle (federal primers) and Winchester ammo. Winchester redesigned their primers in 1999 to make them more sensitive.
If these rifles slamfired once per magazine things would be really bad, if that is your point about consistent slamfires. Have one slamfire and you won't want to have another. That will be one per lifetime.