In "Collections\Photos" or in any folder, with "View option = Gallery" and "folder options \ show folders groups" we saw subfolders of current folder too, instead of viewing all files in all subfolders in one list, grouped by sort option.
Maybe, You can add option "Folderless view" to show all files in current folder and it's subfolders, ignoring this hierarchy.
Somewhat like in Apple OS X Photo - all files stored in subfolders, but you can scroll one pretty big list of all photos with group dividers.