I don't like it either but that's the way it currently is. As Katitof said, a Kubel is probably the best way to skip a Volks into a stall for Obers.
The issue eith those is that their late power level is exactly what OKW needs, which fixes their cost and reinforcement in place. On the other hand you can't fully put their scaling into veterancy so that they can be buildable in the late game.
Earlier Obers must be toned down though, at which point they won't be worth the bleed anymore, especially not compared to STG Volks. Reducing the bleed is impossible because of their strong late game. So where should their place be? Early with too much bleed, or late when appropriate but you can't fit them into the build?
The only way to do it would be to increase the reinforcement cost with the MG upgrade. Or they need tp sacrifice their elite status, which would be bad for the faction as well
Well, there are a few ways that this could be done:
The simplest solution would be to give Obers a tiered upgrade. You might be able to purchase them after the first truck for (for the sake of argument, not an actual suggestion of cost) 290 mp, with a reinforcement cost of, say, 30. A corresponding reduction in strength (in the form of weaker rifles? Lower RA feels like it would defeat the point) comes with this.
Then, for a 50MP upgrade, they would receive their original power level, and original reinforcement cost of 36mp per. Presumably this could come when the Schwerer is placed, and squads built after this point are 340MP, and come "pre-upgraded", in case one needs to replace them for some reason. You may subsequently upgrade the squad with their MG34 as normal.
In this way you would be able to have access to Obers earlier, in order to allow them to vet up a little/fill in your infantry build, though at a power level that doesn't ruin the balance at that stage of the game.
Something similar is what I'd do with Volks, though in the opposite direction. The STG upgrade would ideally be replaced with an upgrade that reduces their bleed, and makes them more effective stalling troops.
I dont think peaple need to make more of an issue with volks than it is, sure their broken vet got toned down and now they might scale a little to bad lategame.
No need to change entire tech structre for a slight 5-10% acc or rec acc buff needed at vet 5
I think the Balance Team have decided that vet 4 and 5 can no longer be "combat" vet levels, they did just remove a combat bonus from Jaegers' vet 5, after all.
In any case, It's not just the vet that's the issue; their STG upgrade is a weird design by itself.