There was a time that the act of writing a program gave the developer full control over each and every transistor of a machine. That era died alongside the 3.5” floppy disk.
An app is a restricted bit of code, governed by the many laws set by the operating system that gives it power. Just as the Android API provides the means by which your app will work for the user, it also places limits upon what your app can do for the safety of the user. That is the underlying principle behind the many convoluted rules surrounding intents and the manifest file, avenues through which the application will request for additional power from the operating system.