OKW upgrades on trucks is a hold over from when they were resource limited. These bonuses were to help them maintain presence on the field because they would have fewer units than enemy. Currently too effective for cost.
In the next patch I fully expect all OKW trucks to lose their free upgrades and require direct tech to unlock.
Schwer is a poorly designed unit anyway since it completely negates infantry play, pulls a point out of contestion until at least one tank is around, gets to shoot down planes (again when OKW could potentially not afford to build a dedicated AA unit), and is a simple upgrade to all other factions tech structures.
This man knows what his talking about. best comment so far.
Lets not forget that ISGs camp around the t4. which allows no infantry to rush in for them.