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g43 and stg I'd say are about equal in different dmg profiles.
For g43 you have the mainline and "special" g43s. As you said you have two completely different damage profiles based on squad, and the game doesnt tell you that.
For STG44 you have close range STGs (Strums), Mid-close range (Pgrens), Mid-Long Range (Obers) and a dmg steroid at all ranges (Volks). Atleast the Obers one is slightly different than the others.
The only other weapon I can think on the allied side that can be confusing is the m1a1 (elite vs RE) for USF or the special Commando Bren for UKF. But I'd argue that one is nowhere even close to as confusing as the Axis ones.
I mean plenty of people on this site have gotten it confused by this (including me) and I'd say the players on the site generally know damage profiles and statistics better than the average player. An average casual player has no chance of knowing that a strum stg is different from a volk stg or a Gren g43 and a JLI g43. Which would explain why a lot of players will always try to get up to point blank with volks/obers when they have stgs. Even if they would be much better of sitting in cover and making the opponent close on them.