For me (on 9.10) the issue with group dirs resolved to be an issue with the list view not showing all emblems.
I have no idea why you are not seeing the correct emblems for non writeable dirs. (even though a lock may suggest you can not even enter the dir)
But I can confirm that dirs owned by another user and group (which I am not a member of, i.e. like foreign home dirs) are missing/don't have the lock emblem.
For me (on 9.10) the issue with group dirs resolved to be an issue with the list view not showing all emblems.
I have no idea why you are not seeing the correct emblems for non writeable dirs. (even though a lock may suggest you can not even enter the dir)
But I can confirm that dirs owned by another user and group (which I am not a member of, i.e. like foreign home dirs) are missing/don't have the lock emblem.