When we use the Google Play Store to install applications, the application will be installed automatically without any Package Installer notification. It does not even require any user interaction when updating applications. It won't do so when we use the F-Droid or others.

pm install some.apkshellrootsystem

Therefore I would like to know how this is done. It would be much more better if codes from https://android.googlesource.com/ can be provided as evidences. Thank you.