Vehicle crews arent supposed to do anything but repair the vehicle and cap. If anything, they shouldnt even exist as the two things they do exist in ability form.
Thompson upgrade is joke. "Have passive-roled infantry that are supposed to be operating your vehicles become assault infantry". Sure. Ill just abandon all my vehicles and charge with my vehicle crews.
That ability needs to be removed, or actually made into something useful.
It's a total waste of a slot, an utter waste. Show me one ability in this game that is as useless?