Why is tautomers not possible in benzoquinone?
You could sort of devise a tautomer by transferring an $\alpha$ hydrogen from carbon to oxygen.  But if you draw the resulting structure you find a pair of cumulated double bonds.  That tends to be unstable, and since the cumulated double-bonded carbons favor a 180° bond angle putting them into a relatively small ring makes them a lot more unstable.  Your proposed tautomer is way out there in energy.

Tautomerization of a ketone works better when you have an $\alpha$ hydrogen on a saturated carbon atom.