Why there is no separation like front-end, back-end development in native apps development?

In Web development world we have front-end and back-end roles. I know we have roles like Full stack developer too but still many companies hire for front-end and back-end roles, and database experts too.

I don't know much about Mac app, iOS app, Windows App, Android development but it seems in that kind of development it seems one person do everything, no separation of roles like front-end, back-end.