There is no single tax rate in the US. There are at least three different granularities of jurisdiction (federal, state, local) and many different types of taxa

There is no single tax rate in the US. There are at least three different granularities of jurisdiction (federal, state, local) and many different types of taxation schemes (income taxes, property taxes, transaction/sales taxes, fees, etc) most of which have exclusions, deductions, etc. and all of which distort the effects of taxation. The Laffer Curve doesn't account for the massive complexity of taxes in the USA nor does it account for the game theory of moving revenues and/or profits to different jurisdictions or transactions moving into the black market.