On iOS at least, apps can't run in the background. Carousel could only upload photos when you open it (or, as a workaround, when your GPS location changes if you've given that permission).
Carousel's "Flashback -- Discover This Day in the Past Year" feature strikes me as a very clever social workaround since it gets you to open the app at least once a week.
The Dropbox iOS app has the same limitation. Presumably you opened it more to do unrelated tasks, so it makes a lot of sense to bundle them.
Google Photos has the same limitation as well on iOS. I find Carousel's syncing and Google Photos' syncing seem to be roughly on par with each other.
Carousel's "Flashback -- Discover This Day in the Past Year" feature strikes me as a very clever social workaround since it gets you to open the app at least once a week.
The Dropbox iOS app has the same limitation. Presumably you opened it more to do unrelated tasks, so it makes a lot of sense to bundle them.
Google Photos has the same limitation as well on iOS. I find Carousel's syncing and Google Photos' syncing seem to be roughly on par with each other.