You don't need to pay to unlock them though.
? They are locked behind your first building. Which is free, but you still need to spend upgrade/build time to get it. Remember they also reduced the cost of molotov upgrade, it only costs 15 fuel to upgrade now (down from 25).
For a faction like OKW that isn't exactly rolling in early game anti-garrison capabilities having the Incen nade cost move than it's Soviet counter-part while being identical is kinda uh, silly.
Volks also don't get added range with Vet, so once Cons actually have in some total better ability vet than Volks do AND better survability vet than Volks do (Vet 5 Voks have .81, Vet 3 cons have .65).
I'll make a thread about this (OKW Vet getting outclassed by other factions with recent changes) later. Give you an idea about how huge the gap has gotten, cons have an effective health versus small arms at Vet 3 of 738 while Volks at Vet 5 have 493, that's a difference of 245 health or 15.5 Mosin hits.