Pay a commander slot to have a fair chance vs enemy stock medium tank, fair enough, tho.
Lets look at that stats:
PzIV vs T-34/76 at range 35, PzIV 86% chance to win
PzIV vs Sherman at range 35, PzIV 62% chance to win
PzIV vs Sherman 76mm at range 35, 76mm 78% chance to win
So yes it is fair and 76mm is simply not trash/useless as people claim.
As for the commander being "fair" or not I would say that is as "fair" as Panzer J for Ostheer.
Does that make commander good? no it does not.
On the other hand USF have several issues like:
1) USF have access to 5 different version of Sherman and their stock Sherman is a very quite efficient tank. As I have already pointed out making all 5 version worth building and balanced is a nightmare.
2) Access to one of the best TDs in game that work equally good vs light/medium/heavy and super heavies tank leaving little room for other AT vehicles.
3) In the current implementation overlap between commanders like mechanized/rifle/(and urban assault) all providing a superior medium tank.
If there is a need to make mechanized company more attractive (and the commander does seem to unpopular) that is not buffing the 76mm which is a cost efficient unit.
Now keep in mind that I am responding to claims that "the 76mm does not have role/it is trash".
If you agree with these claim feel free to explain why but if you disagree, I suggest you argue with the people who made this claims and not me.