They wouldn't ever do that on iOS because it would 'add friction'. Apple makes money off the App Store. They want users to head to the App Store for everything. Developers also want you using their apps, because they can track you better than they could on a website with content and tracking blockers.
It's not the same on MacOS because users aren't going around looking for new apps to install. People install their core programs (e.g. Office, maybe some games), and they get everything else on the web.
Yes. That's part of their profit margin. Just as how the PS5 literally sells for less than it costs to make the console[0], Apple doesn't realize all of their profits from iPhone sales until after purchase where they expect a certain dollar figure from their customers to be spend on either their subscription services or via the 30% app store cut.
This is also happening in VR, by the way - the Valve Index is still the top but the Oculus Quest 2 is insanely close to matching the Index in experience, and that's all thanks to how Facebook literally sells that at a loss of $400, since they want $800 for a version without (1) Ads and (2) their cut from Oculus store sales[1].
> It's not the same on MacOS
Exactly, and I think the pricing difference of these devices reflects that (despite the main cost centers, being manufacturing tooling and labor, having largely similar costs for both). If the iOS landscape turned into the MacOS landscape overnight, we'd see a similar jump in cost for the phone thanks to the lost post-sale revenue.
It's not the same on MacOS because users aren't going around looking for new apps to install. People install their core programs (e.g. Office, maybe some games), and they get everything else on the web.