I initially misunderstood OP. However the more I think about it, the more it seems similar though. If Steam is charging game developers a 30-20% cut, that must mean those game developers margins are higher than 30-20% or there will be no point selling on Steam. It seems that Xbox would be expecting their Studios to operate at the same efficiency as others in the market then, no?
If you're talking about the margins of a video game sale, the gross margins on that are like 99.9% in absolute terms.
You don't seem to understand the difference between the margins on a sale and the averaged margins once the studio development costs are included.
If the store takes 30% you are still left with 70% gross margins but if you have development costs, you maybe only have enough sales to break even or just barely be profitable. A 30% margin on the entire studio means the studio must produce guaranteed successes consistently.
It might also not be obvious but if Microsoft imposed 30% margins, those are a floor, whereas a fee reduces the ceiling. They are not the same even if we assume the target is met.
No, they’re not even remotely the same. The retailer keeps 30% of the retail price and, out of that, they pay for the upkeep of the store. It’s not 30% pure profit, it’s not even gross profit given they need to pay the card processing fees out of that 30%.