at even vets obers actually massacre penals...though understandably so being more expensive and having access to muni upgrades...
the only way soviet infantry can beat axis infantry is with doctrines
and thats where the real problem lies... soviet infantry cannot keep up with axis infantry... simply put... an over reliance on vehicles is a bad thing...
Yes Obers beat Penals at equal veterancy but the difference is that Penals start accumulating vet from the start of the game while Obers are locked behind T4 and have to deal with fighting already vetted up squads at vet 0.
It´s true that Soviets rely on doctrines more than other factions but at this stage of the game there is nothing that can be done about that. Also factions are supposed to be asymetrical, so what´s the problem?
Saying Soviet infantry can´t keep up with Axis infantry in late game is simply wrong. Again, vet 3 Penals or Guards are better than vet 3 Grenadiers and Volks. PPSH Cons are better than Grens and Volks if you have a game on a CQC map. The only way you really lose the infantry fight is if you spam Conscripts without PPSH doctrine, as I said before.
What I forgot to mention is that another way to get into trouble is too many PTRS upgrades on Penals. If you need to handicap yourself with PTRS because your build doesn´t work out then you will pay the price for it in late-game.