Hi hap: There are ways, many ways, to avoid paying income taxes. It's a "gray" area and accountants often make a damn good living creatively bending the tax laws. And yes, the risk is penalties, not jail.
Glad you agree, Trump needs to show his tax returns, especially since he had them changed with his tax cut, unless you believe he has something to hide. Every American files his taxes with the IRS, unless the rules are special for this president.
2nd Trump's daddy cheated taxes along with Trump and his siblings which the NY Times exposed.
Trump has inflated and deflated assets whenever it was to his advantage and with taxes, financial institutions, and insurance companies that's called fraud.
Trump is a crook. His Daddy was a crook. His Grandfather was a Pimp and Drug dealer. The apple doesn't fall far from the tree.
Trump has stiffed small vendors and hapless people (see Trump University) what makes you think he hasn't stiffed the IRS? How naïve but then there are people who are full fledged members of the Trump cult.
Oh and you seem to know very little about taxes and income. The only item you do not have to prove for tax purposes is income. That's up to the IRS to prove.