Uh, there are only 2 heavy TD's in the game, only 3 heavy tanks in the game, SP's aren't engineers and cost far more, Volks are the worst starting infantry in the game...
All these things cost more than what you are comparing them to, again:
More expensive units are better then less expensive units; more at 11.
Do you rememeber when 3weeks ago you said to me that SP are not Engis and then week ago you named them yourself as engis?
So what if there are 2 or 3 units like that? All belong to OKW. It does not matter how many of them are in game.
Worst starting inf which turns into bullet immue tank hunters.
Cost does not matters.
It's about design where OKW has best of the best.
Panther is a way more expensive than T34, yet it arrives in very smiliar time to T34.
KT is the most expensive tool yet I can hit the field around 15-17min in 4v4 and still minutes before IS2 in 2v2.