Well especially on 3v3+ the whole map usually eventually gets filled with caches, but most of the time allies are more manpower-stricken in my experience. Although this might be due to the fact that when I play okw I play aggressive like allies and try to bleed them as much as I can, since it's annoying as hell as allies to have that done to you (and I'm tbh mostly an allies player). It did also sound like you were saying okw still got that reduced fuel income, but that's just a simple misunderstanding.
Okw does also get to salvage their own kubelspam and other people's shitty team weapon spam, as stated above.
Yes thats true, but in 2v2 - with the current state of Ost - two OKWs is not too surprising = no caches. For 3v3 and 4v4 I cant speak, but balance in those modi is broken anyways or at least totally different from 2v2s.