No rewards from their tech buildings for the SU/OST. They already have to retreat their busy engineers to build tech buildings. I'm always annoyed when I have to retreat my engineers and can't plant some mines on the frontline, or use the flamethrower which is just bought a few seconds ago. Thanks to their busy work. Probably the SU/OST engineers are the busiest of the whole game. It really makes me LOL when I see the UK tech buildings can be built even without workers.

But then still no rewards for the SU/OST from their engineers' hardworking:
no retreat point(make the SU/OST hard to goback to the front)
no fast repair speed(so you always have to build 3 engineers to fast repair their heavy armor, even make them much busier)
no free squards/flak
etc.
A lot of suggestions has been talked. Maybe they can use some upgrades to buy repair speed boost? And at least retreat points?