Why don't the guns do the correct damage?

I've done the same tests you have. Taken a weapon and counted the shots and considered the distance. Fewer closer than further and that makes sense for a FPS game. However, when playing against players, the inconsistency of kill to hit ratio is very unpredictable and very inconsistent.

SMGs for example... They take many hits beyond the "close" range and many times players will react to you shooting them and take cover. However, for me, on a PC, the SMG damage appears to be stacked on the server side and delivered to me all at once resulting in a very very low TTD to almost instant death. This is commonly referred to as "super bullet" and I was introduced to this mechanic in BF3. This issue has followed the franchise with every title release. I've recorded a handful of instances where the death, damage summary would show that I was killed by an SMG in two hits. That's two rows of the SMG icon and 50 damage output. Is that even possible with that weapon platform even if they were point blank and headshots? This screams "super bullet" from the server.

The only other option I can think of is to use the performance meter displayed so that you have a better sense of when you shot someone and the server acknowledged it vs. when your client side detection acknowledged the hit but the server disagreed and dusted your shots. At least you get the confirmation that it's not you.