I think this is zero marginal cost income that they receive from something they created to sell their core product (devices). They essentially need this app in

I think this is zero marginal cost income that they receive from something they created to sell their core product (devices). They essentially need this app infrastructure to support their device sales and the idea that the developers are financing it or that some are free riding is just silly. This is money that apple can get for free and they choose to give up some of it because it benefits them to have more apps and more developers so they can sell more devices. You just don't notice it because they have built their business to a size where they have a network effect advantage and aren't desperate to get every developer they can if they were a smaller player.