They seem to be doing just that: https://security.googleblog.com/2019/01/pha-family-highlight...

The problem, is the author doesn't always know his apps are stolen.

Sounds like they could do with an automated plagiarism detector, although that has its own gameability problems.

Doing this in a fully automated way that works well is tough. Blindly applying DroidMOSS falls over against simple techniques.

Add to it that lots of repackaged apps are distributed outside channels that Google controls and you've got a hard problem.