Are you absolutely sure that volks have worse snare and nade ?
Yes, by vet 2 and vet 3 both become better than volks utility, with molotov still being cheaper and both snare and molotov being paired with oorah
The upgrade you are referring to comes into play after t4 installment, volks can have theirs way earlier, they also beat cons without it. Basically without a flamer, significant number advantage or better cover/positioning it is very hard for stock cons to win this matchup. That is why SVTs are so popular - they eliminate early game weakness of cons.
It doesn't matter when it comes, volks have a powerspike of 3 minutes after their stg upgrade and that's it for them, they'll become the underdog of any matchup while being more expensive and bleeding more.
Vet 3 normal cons still trade much more efficiently against stg volks while having no muni cost upgrade. The difference is not up to debate because we can pop cheatcommand anytime and see objective data
molitov is not better than the lava nade
It is by vet 2 Cons, which is what I said. It's also arguably a sidegrade already from the start with the slower throwing speed since it's paired to a non doctrinal rush ability
The stg upgrade isn't special for upgrading dps at all ranges, most upgrades now do it, including comscripts doctrinal and non doctrinal upgrade and most allied upgrades. It's also a intellctually dishonest argument, no upgrade is "bad" over the base version, even if it is more oriented at specific ranges. The ppsh conscript upgrade make dps at range worse but nobody in his right mind would ever want a normal unupgraded version of cons over ppsh cons, if the other upgrade options weren't avaiable.
According to what metric is the Stv upgrade popular? How much time was he used in the ongoing tournament? Everyone goes for 7 men coms without issue and cons never struggle throughout the game