I completely agree too.
About enemy's road/RR/maglev :
road work for everybody the same
RR work in enemy teritory only after you control X tile
Maglev the same but after a bigger X

.
That means that you capture trains, depos etc.
For enemy's tile control I sugest the idea from The Operational Art of War : tile is under control of that civ who had the last unit there; one tile around the resting units.