Please note the following are assumptions based on my Linux knowledge. So I cannot 100% back them, especially cannot tell if any/all recoveries work this way.
First, some raw facts:
- as already pointed out,
/data/media
is a symlink to the SD card
- resulting of that, the data behind it reside on a different partition
- that other partition is usually not included with the wipe/factory-reset, which normally covers only
/data
and /cache
So now to the wipe itself. "Emptying" the /data
partition could be done in different ways:
- "formatting" the partition: wouldn't touch the data behind that symlink
- performing something like
rm -rf /data/*
: would remove the symlink, but leave the data behind it untouched
- walking the entire
/data/*
file by file, directory by directory, removing each entry (no idea why one would do that). In that case, unless the process follows symlinks, again only the symlink would be gone but the content behind it left untouched
So once more: As the data-in-question does not physically reside on the /data
partition, it should even be expected to stay.