You're complaining about only 10 troops in a C-47 when you don't question the fact that airfields are controlled by 1-mile square mini-towns with a maproom in the center and 10 guys jogging at a medium pace instantly "take control" of an airfield by going into the map room?
It's a gameplay concession. There has to be a limit, a structure, a rule for how the capture works. If they chose "10" troops because it was a round number, then whatever they chose is exactly 1 planeload of troops.
Meaning 1 capture per sortie. Not meant to be realistic. Meant to be gameplay-balanced.