My beef with the Laffer Curve is that it only demonstrates the optimal tax rate, revenue-wise, not that the gub'mint actually needs to extract that amount to function...
It should go without saying Dems are more interested in power than optimizing revenue, hence the emphasis on higher, but much less efficient, not too mention counter-productive and punitive tax rates.
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THI-I-I-S-S-S-s-s-s....
....was precisely my point in my little impromptu blurb.
Thanks for your analysis.