It works better because iOS had this for many years and apps implement it natively. Android's implementation is basically a workaround. The back gesture is recognized by the system and forwarded as back button event to the app. On iOS the gesture is handled by the app, which can provide proper animation, giving users the ability to “preview” what’s behind (and pull back to the left to stop going back). Android is trying to copy that right now (as they should because it works really well), but it will take many years for apps to adopt it.