No, you misunderstood. I'm saying it wouldn't be less investment, not that it wouldn't be faster
This is literally why you lock it behind t4...
Looking at T4 as an investment to engineers is weird way of looking of thing but rather irrelevant.
Point is that EFA would have access to far more cost efficient repair engineer since the unit would cost less and yet be able to repair at similar speed.
It says exactly what it says, they currently have better repairs
USF have crews on top of their engineers, OKW can get the mech HQ repair station on top of their engineers. Brits can get extra man on engineers, can upgrade their repairs further with one of their t4 paths
I am not sure what you mean by better since:
OKW mech truck has a cost and a tech choice attached
UKF heavy sapper have a munition cost and a tech choice attached
so they are not really more cost efficient.
All the while all 3 of those factions engineers can have MUCH better combat after equipping a sweeper
Not really unless they also equip a weapons. Sweeper should take up 1 weapon slot for WFA but that is another story.
On the other hand EFA can equip flamer without a doc and have other perk as well.
There was a time that WFA had more cost efficient repair speeds but that is simply not the case any more after the repair speed patch.
EFA simply do not need shared veterancy and minesweeper repair boost, since the are fine.