I've searched around for this, and all I can find is the usual "i'm an admin but need to elevate" kind of questions. This isn't quite the same.
I have a D drive on a file server (2008 r2 and same problem setting it up on 2012 too) with a folder which is shared out to users. Everyone has access to the entire shared drive over the network, apart from a few folders which only specific groups can access.
I set this up so that those specific sub folders stop inheriting permissions and just give full access to the groups in question (nothing to do with admins). I have a domain user which is a member of the backup operators group and all the local backup operators groups on every machine in the domain (set via GPO). This user is used to run a file sync program in order to sync the fileshare to a NAS every night for backup. This software also runs on the machine in question and not remotely.
I gave the user the ability to logon interactively so I can setup the software under that account and test that the backup works before I create a scheduled task for it.
The problem initially was that the software failed to access the more protected folders - which as far as I was aware wasn't possible with backup operators. So instead I added the backup operators group explicitly to those folder permissions with full access - the same error. So using explorer I went to find the folders in question - and note I'm not running as an admin, however despite this windows asked me to elevate.
Now this is the question - why on earth does a non admin account require an admin token to access a folder it has full permissions to (via it's group backup operators)? This is not in a system folder, or system drive, it's just a normal drive, under a bunch of normal folders with some slightly tighter restrictions on them.
I really don't get why UAC is even needed in this instance - it's got nothing to do with administrators!
Permissions on folders as requested by the comment:
C:\Windows\system32>icacls "d:\share\support\tech documents" d:\share\support\tech documents QUT\access tech docs:(OI)(CI)(F) QUT\Domain Admins:(OI)(CI)(F) BUILTIN\Backup Operators:(OI)(CI)(F) Successfully processed 1 files; Failed processing 0 files C:\Windows\system32>icacls "d:\share\support" d:\share\support BUILTIN\Administrators:(F) Everyone:(I)(OI)(CI)(M) BUILTIN\Backup Operators:(I)(OI)(CI)(F) QUT\Enterprise Admins:(I)(OI)(CI)(F) BUILTIN\Administrators:(I)(F) CREATOR OWNER:(I)(OI)(CI)(IO)(F) NT AUTHORITY\SYSTEM:(I)(OI)(CI)(F) QUT\Domain Admins:(I)(OI)(CI)(F) BUILTIN\Administrators:(I)(OI)(CI)(IO)(F) BUILTIN\Users:(I)(OI)(CI)(RX) BUILTIN\Users:(I)(CI)(S,AD) BUILTIN\Users:(I)(CI)(S,WD) Successfully processed 1 files; Failed processing 0 files
The folder above the one in question is simply inheriting permissions, the tech documents one has inheritance disabled and explicit permissions set.