Fake GPS and overlay apps

It seems odd to me that apps like fake gps and fly gps appear to have millions of downloads on the app store and get only a handful are reporting bans using them.

I used fake gps 3 weeks ago myself and haven't had any issues.

Any current theories floating around as to why that might be? Are they just having a hard time detecting overlays vs emulators like NOX and Bluestacks?