It appears the sandbox for store apps makes use of junctions, so the disk space used is much lower than it may initally appear. Even in the first screenshot of the thread, the actual allocated filesize on disk for "2.5 GB" of binaries is only 60 KB
This can be validated by checking the localcache folder size in explorer:
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or by running "dir /al /s" from a cmd window in the localcache folder.
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Note the parenthesis around the filesize, which represent a junction of some sort.