If they’re root, they already can. Like Google Play and other root/system apps that can install apps without the pop-up.
It is an obvious double measure but it’s been around for a long time, and it’s not too insecure or annoying unless manufacturers install malware as system apps and/or disallow locking the boatloader (they do, sadly).
If they’re root, they already can. Like Google Play and other root/system apps that can install apps without the pop-up.
Fun reminder that the Facebook system apps included on many phones can do that too. Look for system apps called "Facebook Bridge", "Facebook stub", "Facebook App Installer", "Facebook App Manager" etc.
I would not like everything to run as root. But an option to root your phone without too much hassle and make any changes to app permissions would be great.