It seems Windows Explorer does not include the sizes of "hidden" files when calculating the parent folder size, even when I check "Show hidden files, folders, and drives" in the "Folder and Search Options". When I hide a folder, Explorer reports it as empty when I mouse over it, even when there are files &/or folders in it. A similar issue arises with "Operating System Files and Folders", or files hidden and often inaccessible to the average user that control how Windows operates and are very dangerous to mess with.
Why does this happen? Also, is there a way for Explorer to include these files/folders when calculating the parent folder's size? Perhaps including other users' files/folders, even if you can't access them? Even for files you are not allowed to access, knowing the size of the folder seems important.
For me, this is happening in Windows 8, but I wouldn't be surprised if other Windows versions did the same thing.
I would like the solution to work right in Windows Explorer, but any solutions, including ones scripting languages, is fine.