Hughes, in war, you aren't trying to have a fair fight, you are trying to have an edge, since the intent is to win. Also, that multi million helo can kill hundreds and hundreds of that "lone infantryman" so long as nobody with an SA-7 shows up to frequently.
The asset is reusable.
Army has recently been fielding 2.75" rockets with seeker heads on them. Same old weapon, but now it can be directed. Much cheeper than using a fancy Hellfire to take out a car.