I am not defending the absolutely awkward pricing model of Unity.

Do you think we should also give them a flat 30% then? 1/3 of your gross is massive, and we could argue Unity is just as important in the execution of your game.

As far as I am concerned the comparison with retail does not hold. Retail runs on thin margins. Steam on the other hand is absolutely massive and afaik is one of the most, if not the most profitable business per employee in the USA. It is absolutely greed.