The reason Trump skipped over those details, while suggesting his plan would accomplish something very different, is that Americans tell pollsters they want something very different.
In a Gallup poll from April, six in 10 Americans overall said upper-income earners pay too little in taxes. They've said the same thing in Gallup surveys going back a quarter-century as income inequality has widened in the U.S. economy.
The blue-collar white voters in Trump's base feel the same way – even more strongly. In a post-election survey by the Democracy Fund Voter Study Group, 75% of Trump's strongest bloc of supporters called for higher taxes on those earning more than $200,000 per year.
In his Springfield speech, Trump also vowed to boost the American economy by freeing Americans companies of what he called an oppressive tax burden. Combining the top federal corporate rate of 35 percent with state and local taxes, the president said, the U.S. has fallen behind France, Germany, Canada, Ireland, Japan, Mexico and South Korea, among others.
"We have totally surrendered our competitive edge," he said.
There are two political problems with that call for lower corporate taxes.
First, Trump lately has been touting the robust health of American business. "Corporations have NEVER made as much money as they are making now," the president tweeted on August 1.
Second, most Americans want corporations taxed more, not less. In that April Gallup survey, 67 percent of Americans said corporations pay "too little" in taxes, while just 9 percent said "too much."
That doesn't make lower taxes on the wealthy and business unwise policy for Americans overall. Democrats say economic gains under Presidents Clinton and Obama show that top-end tax increases don't harm growth; Republicans insist growth would have been higher without them.
But they underscore why the White House and Congress have fallen far behind their initial schedule for tax reform, under which a Republican plan would have already been passed into law. Their plans smack headlong into public opinion, just as their failed attempt to repeal and replace Obamacare did.
House Republicans, just like candidate Trump, last year proposed a plan that would have delivered much larger gains to the wealthy than to the middle class. Now the White House and Congress are struggling to develop a unified approach – on tax rates, tax benefits and federal deficits – that can withstand the political heat that comes with actual votes on Capitol Hill.
That could include heat from Trump's own hard-care base, to which he has clung ever more tightly as his overall popularity has fallen. The president's tax team, as well as the gap between rhetoric and policy reality, encapsulates the challenge.
In the Democracy Fund post-election survey, 63 percent of the president's strongest bloc of supporters expressed hostility to Wall Street. Trump's point men on tax reform: Treasury Secretary Steven Mnuchin and National Economic Council director Gary Cohn – both veterans of Goldman Sachs.