Why would they bother with something like that when they have synths? They obviously do not care about individual lives so using living weapons/warmachines has no downsides to them and those are presumably better than mere drones since they do not use drones (apart from the flying blades that CP use.)
And I know that the Combine troopers also use some of the stuff humans have but it is clear that the BEST stuff is unavailable to the CP.
If I recall correctly, the Hunter Chopper made up for it's lack of agility with a far more powerful arsenal that includes it's timed mine. Despite these being somewhat shitty against Gordon, they're quite effective against the Rebel's fortifications. In addition, the Chopper is crewed by Overwatch Soldiers which implies it's a cross service vehicle.
Now, let's compare it to it's supposed "Overwatch counterpart". The gunship is far more accurate with it's pulse cannon and has no other weapons that are used in game. It's less of a attack helicopter than a vehicle meant for accurate surgical strikes.
The APC isn't the Strider, by a long shot. That's because it's meant to serve a entirely different role in combat. It's not meant for directly engaging a large group in advance, it's used to deliver the Civil Protection to trouble spots so they can subdue a foe with ease.
The thing is, humans are valuable resources for them. The Combine needs us and other species to fuel the war machine, in order to continue their conquest. Thus, why they put so much effort into brutalizing us into complacence. You think that they would give a shit about the blue mound of feces that is Earth otherwise?
