I said 'can', not 'should'. This isn't an 'if X then Y also' situation. Unit price is partially independent of comparisons between factions and can be based on certain performance or faction balance/needs. The fact that some units are priced for initial value (Grens) and others are priced for max potential (Obers) proves that. There would be no need to (significantly) lower Penals price if they were to get an SVT upgrade package as it could upset balance more than is needed.
Except scaling completely turns upside down vet0 balance.
If you want to scale to maximum performance, then that also means cost decreases for penals, because they stand nowhere near similar infantry like pfussies or rifles who got much more utility and abilities.
That's why vet0 cons vs grens are perfectly balanced, but the very moment lmg upgrade comes into play, its one sided combat. You have additional cost of that scaling, its a munition cost of the LMG upgrade, munition cost of BAR upgrade, of pfussi G43 upgrade.
And no, you can not ignore cost relations across the factions of units performing similar role.
Just look at medium tanks.
P4 of both axis factions have best stats and have edge over all allied stock medium tanks, should we increase their costs even further?
Obviously no, they already are more expensive.
And so are penals.
You are trying to fix what isn't broken.
By going penals you sacrifice map presence and map control, you will always be outnumbered and you will always be outcapped, that is why they need to be winning early engagements they participate in and in case of their scaling, its not better then any axis units scaling, they get in offense what they lack in defense, but they do not have any weapon upgrade which would increase their main role of AI infantry, contrary to both grens and volks and even pfussies if you want to go for them. Hell, even osttruppen get LMG upgrade now to scale even better despite them being supposedly trash, throw-away meat shield infantry.
You want to see less penals?
Come up with an idea to make cons a viable pick that wouldn't be a massive burden in late game without doctrinal aid.
You'll nerf penals in any way now and we're back to maxim + guards spam.