While these are all fun and valid criticisms of the game engine's limitations, regarding the original "invisible bug" point, due to the scripted requirement to be in a squad in order to man assets, it does in fact make it easier to know who is one-manning.
Unless you have proper knowledge of which asset type is strictly for bots/players on a given map, by scanning through the players manning asset(s) and accounting for them on the map, you can tell immediately that a player is one-manning if they appear manning an asset but cannot be located through choosing them on the map or squad management panel. I have been using this method, since first noticing the related limitation, to effectively pinpoint one-manners and encourage them to go back and man assets properly, or take administrative actions against them if they become uncooperative.