How to clean up camera roll/All Photos on devices with shared iCloud account? I have quite a few iOS devices on the same iCloud account and the "All Photos" (camera roll?) keeps propagating >9000 images/videos between all devices.  I would like to get to "Camera Roll Zero" and reclaim all space being used by Photos at present.

Each time I connect a different device to my primary Mac, it appears that all photos appear again in apps like Image Capture.app, while Photos.app continues to show the old photos at the top in the import pane.  

I've discovered a handy little app called PhotoSync.app for iOS and a helper app on macOS that seems as though it will do a "proper" syncing vs the junk that Apple does, but the program is gagging with having such a HUGE camera roll.  Whenever I run it, it starts downloading images from iCloud during the transfer process.

So I'm hoping to figure out how to sanitize all of my iOS devices so that I don't have this enormous collection that still uses several gigabytes on my iOS devices even when I supposedly don't have any photos/videos on the device and my "Recently Deleted" album is at 0.
Make sure you have a backup of your images before trying this.

In iCloud settings, turn off iCloud Photo Library and My Photo Stream for all your iOS devices, including your Mac. Also make sure photo syncing is disabled in iTunes, just in case. Now connect each device to your mac and launch Image Capture. Select all the images you don't want, right click and select "Delete x Items". Do this on all devices before turning iCloud Photo Library and My Photo Stream back on. This should force iCloud to reset your My Photo Stream and iCloud Photo Library.