I noticed this on GNU/Linux but I believe this feature does not depend on the OS.

Folders are listed with the size column showing the number of items inside the folder. This is useless for determining which item in a folder uses up the most space on the volume.

Instead, the size column should show the amount of storage space that folder takes up (in KB, MB, GB, TB, etc.). As the folder's content changes, the size is recomputed keeping this information updated.

I understand that implementing this will generate a lot of disk/network access and that's okay. I'd like to have the option to see this information because I'd like to have an always-updated view of which folders occupy a lot of space. I'd like to get this information without another program (such as K4DirState) or running:

  du --summarize --human-readable * |sort -hr |less

on the command line to get a list of items in the current working directory sorted by their size (largest -> smallest).

This should be a togglable feature set to off by default, as it is in MacOS's Finder. I'd like it if one could turn this on, wait while the folder sizes are computed, and sort by size in a more meaningful way (no more using radically different units for folders than files).