From the engagement you're referencing from the replay, the USF player stayed at range in open cover versus volks in green cover, then advanced through red cover to said volks.
I have experienced a full life RM on yellow cover losing or calling draw vs a full life volks no cover at mid/long range.
I have experienced a lot of situations where Volks simply beat RM on short distance due to RNG factors or simply using a grenade.
We have to be honest, voks trades very well vs most expensive infantry.
Volks get STG on the field while RM need to retreat to their barrack
Volks STG is egal to RM+1 Bar, which let them trade favorably for a long period of time.
Volks get flamnade with the first truck.
Volks get MG34 support from any truck build.
Volks have Sturmpioner as support unit which let them trade even more favorably vs 2 RM/Penal/IS/Cons or whatever infantry you want.
Volks flamnade is just a reverse factor on too many situations. I understand OKW need them for clearing building and flamnade are perfectly fine for that. But on the open field, it is just an OP grenade that deny cover and let you finish your opponent with your STGs.
I have been playing a lot of random 2vs2 games on allied side lately and every single game is the same story. My parter, Brit or Sov get reck after 10 minutes. So maybe the matchmaking is joking me assigning me everytime a dump partner or simply they can't do shit vs what have become OKW and in some extend Ostheer.
My only victories are when the system assigns me another USF player now...