The apparent failure to mirror "correctly" left and right in this illusion reminds me of a great interview question I heard: why does a mirror reverse things left and right, but not flip them top and bottom?
It can be fun to watch people scratch their head over it.
Are you implying _two_ eyes? Because if you think that's the reason, just try closing one eye and looking into a mirror and you'll see that nothing's changed.
(Also, as an exception to your statement, I have eyes, and I wasn't able to grasp why it happens until I watched a video about it.)
It can be fun to watch people scratch their head over it.