It’s simple really.
Apple makes and controls the hardware and the software for their devices. In the app stores it allows for third party developers to make apps for them (similar to other software for Macs) and only sold in their App Store. Apple controls everything and will go after makers who try to make a Mac or iPhone and use Apple software for them. Only Apple can use their software and for their hardware they design to work with them. There are things like Cydia for jailbroken iPhones and there are some markets but you have to jailbreak (break out of the controls from Apple) to get to them. That is the walled garden. Everything is good, clean, and works in the garden partly because to sell it in the garden Apple has to inspect it like they do in their app stores before an app is sold there. Start using things outside of the Apple eco system and they may not work as well or as expected (some do and some don't ).
Its interesting because many Android people will say Android is free to use any app market….freedom…ma freedom…blah blah blah. However when ever I bring up the issue about well then what about Huawei using the free version of android without google services and using those same markets for apps they always say “well those markets are full of crappy and unsure software”. Exactly, pot meet kettle.
Apple makes some great software and hardware solutions for the average person and they have been that way since the beginning. To make a simple to use computer system or device so the average person can use the technology and do great things with it. By limiting that hardware and software to do what it is supposed to do (limiting options) they can employ reliability and steady performance across many things.
Old cartoon but it gets the point across now and then with Windows and Android.
This is also true too.
Thanks for reading....