Because (since they control the platform/market) they're giving themselves an unfair advantage over competitors.

Example: iCloud photos backup can upload a photo to iCloud in the background immediately after it was taken. Competing cloud storage providers cannot do this[1], because Apple withholds the API for that. Of course they're saying this is for "privacy" or for "energy saving" or whatever, but the actual reason is of course to make the user experience with competing services deliberately worse, so that people choose iCloud over something else.

[1] There is some weird tricks with notifications and location triggers that apps like Nextcloud or Immich go through to make this work at least somewhat but those are hacks and it's also not reliable.

> Competing cloud storage providers cannot do this[1], because Apple withholds the API for that. Of course they're saying this is for "privacy" or for "energy saving" or whatever, but the actual reason is of course to make the user experience with competing services deliberately worse, so that people choose iCloud over something else.

Which makes Google Photos so much more impressive because it's heads above iCloud in this regard. No idea how they do that, pure magic.