Android does have a unified calendar that every app push into.
It has two problems (that are both dealbreakers to me): it's not easy to make it push the complete schedule into any other calendar (if it's possible at all, I never managed to), and the apps are often not reliable (probably because they don't want to allow a centralized calendar, the MS ones are serious offenders here).
It has two problems (that are both dealbreakers to me): it's not easy to make it push the complete schedule into any other calendar (if it's possible at all, I never managed to), and the apps are often not reliable (probably because they don't want to allow a centralized calendar, the MS ones are serious offenders here).