After reading the PDF from the Apache forums:
On realistic settings, it takes an inordinate and unrealistic amount of time for petrovich to switch from GROUND to INFANTRY.
I understand that this is based on the geometry of the angle of the size of the object, in this case infantry, in comparison to his view. This is unrealistic because at the point where he has recognised an APC, he is still unsure whether he us looking at a man or a truck. This would be one of the first things he knew, and the geometry factor has made it the last thing.
Perhaps this can tuned.