Terrible Drive UX:
1. Assign rights to a folder to several people.
2. Create subfolders, and everyone inherits rights to them.
3. Decide to remove all but one or two people from one of the subfolders. The Google UI DEFAULTS to removing them from the entire tree!
And that's how most of an event planning committee lost access to all shared files, until I found the person who had accidentally not noticed the little checkbox, and they re-shared things.