As cute as this comment is, a Sniper is the most effective counter to another Sniper. A Kubelwagen, for example, is not going to counter an opposing sniper if your opponent is at all aware of his surroundings, particularly not in a 2v2. Also as others have stated; the current non-sniper sniper counters take significantly more investment to succeed than the sniper itself requires to perform his role.
There is no real reason for OKW and USF to lack this type of unit, do you have an argument against that statement other than a snide remark?
OKW or USF with a sniper would probably be OP as hell. USF only needs the m20 to be put around M3 level of firepower and accessible after first tier tech.
A kubelwagen gives you opportunity to chase and kill a sniper + its vet1 abiltiy, it isn't going to do it all by itself but at least you're not helpless during 6 minutes against it.