Because Apple is willing to eat the cost for the benefit of having a free app? Every free app in their store is one more reason for you to buy an iPhone. Paid

Because Apple is willing to eat the cost for the benefit of having a free app? Every free app in their store is one more reason for you to buy an iPhone. Paid apps, while also adding to the ecosystem, do not offer the same value to Apple. It's also just plainly logical. You can't charge people to give something away. You can charge money if you're helping them make it.