You can argue that the app store and vetting process itself is worth up to or over 30% (i.e. they are giving value away, not extracting it), but they make a clear distinction.
Uber's profit margins are about 10% value created and 90% exploitation of power imbalance between the rich corporation and itinerant drivers and less well capitalized competitors.
Whether somebody acknowledges this reality or not tells you where their political allegiances lie.
That feels like a number you are just making up based on hating Uber.