and the OKW Opel ambulance has 240HP and enough armor to bounce a decent amount of small-arms fire because....?
Doctrinal goodie in a commander that isn't that good outside of city maps is fair I'd say. USF doesn't need to sacrifice powerful doctrinal (late game) tools for a forward ambulance. Besides that the higher health and armor are simply leftover characteristics from when it performed more like a half track, and could easily be brought down to Ambulance levels. Though I don't see the need for that.