I don't think "evil Nazis" should lose every game, I do think that it's macabre in general to reduce this disgusting conflict to a game but that's a completely different issue altogether.
I know that all sides produced prototypes that never saw action - you're not saying anything new. You're not actually responding to my point, you're reiterating your argument and accusing me of bias, something you loathe other people doing.
The "question" I'm referring to is "is this unit 'authentic'?" when referring to things that should be included in the game, particularly when it comes to things which actually saw combat. The Sturmtiger is a great example of my point - it's a purpose-built machine for a very specific battlefield problem. The British made tons of those types of things, but the reason why the Sturmtiger was deployed on the battlefield, outside of its intended purpose, and why combat-ready units like the Meteor were deliberately kept out of combat, or why things like the Black Prince or Tortoise weren't produced and deployed was that the British weren't losing the war and didn't need them. The question of combat use is therefore biased in favour of German tech for the reasons I've stated. Hopefully that's clear enough for you.
Compounding it is the mystique surrounding the Wehrmacht and their supposed wunderwaffen, something that the Company of Heroes series has gladly fed for sales and what the historical community has long debunked. Again, though, that's a completely different issue, albeit one which has effects in this arena.
Glad to see that you agree that outcome of the war has no real bearing in the design of a game. And I have to guess that "reducing" any war in a game is macabre so that applies to most "violent" games.
The "imperialistic army of the British empire" did have many designs (see Hobart's Funnies) some of which where used in combat and some of which never made it to the frontline.
The "nazi Wehrmacht" also had a number of vehicles that also never made into battlefield.
The question weather a unit was actually deployed in front line has no "bias" or "favor" and presence of more units does necessarily translate to advantage of the faction with more unit.
In COH2:
Ostheer have access to around 18 different vehicles
UKF have access to around 14 different vehicles
Soviet have access to around 14 different vehicles
but the number of vehicle does not really "favor" of a faction.
Relic has not promoted "wunderwaffen" it has created asymmetrical balance where axis faction in general get more expensive vehicles that perform better in order to balanced against cheaper more numerous units. That is historical accurate since in general the German army was fighting in inferior numbers.
As for the "historical community" imo it should be more concern about debunking the myth that WWII was about democracy fighting totalitarian states (since the same myth is still being used today, see the Iraq invasion) than weather Sherman was a better tank than the Panther.