Donald Trump called into “Good Morning America” on Friday — a show that tapes about a dozen blocks from his house — to talk taxes with host George Stephanopoulos. The tax talk wasn’t about Trump’s tax plan, which has been its own confused topic of conversation this week, as observers try to pin down what, exactly, Trump’s plan is. Instead, it was about Trump’s own taxes, which, as has been noted, Trump has no interest in discussing.

“What is your tax rate?” Stephanopoulos asked, hoping to at least suss out the most basic bit of information Trump’s tax returns might offer.

“It's none of your business,” Trump replied. “You’ll see it when I release.”

The second part of that response is perfectly fair; campaigns like to massage the roll-out of potentially harmful information and so will hold details until they’re ready to do so. But the first part — telling a member of the media that he has no right to know information released by every single presidential candidate in four decades — is not.

Donald Trump's stance on presidential candidates has changed significantly over the years. Here's how. (Peter Stevenson/The Washington Post)

On Wednesday, Mother Jones published an article detailing a number of members of the media who have been placed on an apparent “blacklist” by the campaign, including reporters from the National Review, the Des Moines Register, Univision and the Daily Beast. Rejecting press credentials for reporters from these outlets is likely less about preventing coverage than about a punitive response to coverage; after all, the events get covered anyway. But it suggests that Trump's initial reaction to Stephanopoulos is his default one: It’s none of the media’s business what he's doing, and covering him is a privilege, not a right.

Stepping back, it also reinforces another point about Trump: He’s almost certainly the least transparent candidate in the era of modern media.

Consider his policy proposals. Trump prides himself on the ambiguity of his positions, suggesting that one must maintain an air of unpredictability — a helpful hedge when asked how, exactly, he’s quickly going to eradicate the Islamic State. (Now that he’s back to wanting to do that, instead of suggesting that the fight in Syria be left to Russia, as he did last autumn.)

On domestic issues, the mantra is “flexibility” or "negotiation.” Nothing, including his tax plan, is set in stone but is instead a point of negotiation.

Unless you want it to be set in stone, in which case he gives you more than enough chatter to think that it will be. What’s missing is the bedrock of Trump’s negotiations — the bottom line. Because if you take a firm position, there will be a voter who doesn’t like it. Voters are left seeing what they want to see. Trump’s opponents are left trying to punch a ghost.

Trump was also on NBC’s “Today” show on Friday. Host Matt Lauer pressed him about wavering on his proposed ban on allowing Muslims into the country.

“[A]re you softening your stance and using subtle differences in words simply to be more moderate to try to attract people like Speaker Ryan and to get an endorsement?” Lauer asked.

“No, I’m not softening my stance at all,” Trump replied, “but I’m always flexible on issues. I am totally flexible on very, very many issues, and I think you have to be that way.”

As the New York Times’s Maggie Haberman put it on Twitter, “Premier example of why people hear what they want and he’s said both things.” Trump’s policy positions are the political equivalent of your parents tossing you in the back of the car and telling you you’d see where you were going once you got there. Maybe it’s Disney World! Maybe it’s the dentist. Who knows?

Even while the Internet has increased the ability to share and process information, our presidents have gotten more reluctant to share information. The George W. Bush administration faced criticism for its lack of transparency, including changing the Presidential Records Act to make the White House more opaque. According to the reporters who cover the White House, the Obama administration has been worse on transparency, despite Obama’s campaign pledge to be the most transparent in history. Neither Bush nor Obama, though, masked his key policy positions in a smoky haze while campaigning or did their best to hide their tax returns.

The tax return issue is a neat encapsulation of the Trump problem. Trump told the Associated Press that there was “nothing to learn from them” and that he didn’t think voters cared. (Republican National Committee Chairman Reince Priebus echoed this in an interview on Fox News.) But 18 months ago, no one would have cared about how Hillary Clinton’s email system worked if you’d asked them. The issue is precisely that: Voters should not be asked to decide on a candidate on faith, but instead should be presented with the information they need to make a educated decisions.

Trump also went after The Washington Post on Thursday, by way of The Post’s owner Jeff Bezos and one of the other companies he runs, Fox News’s Sean Hannity asked Trump about The Post’s planned book on Trump (which was announced publicly last month). Trump hammered Bezos, attacking from an unlikely front.

“Amazon is getting away with murder, tax-wise,” Trump told Sean Hannity. “He’s using The Washington Post for power so that the politicians in Washington don’t tax Amazon like they should be taxed.”

It would be easy or flippant to question whether anyone cares about Amazon’s taxes, but it’s obvious that they do. Amazon is a publicly traded company, and stockholders are given regular updates about what the company takes in, spends and pays in taxes. It is transparent, because it has to be. This is how Trump is able to suggest that it’s getting away with murder, because he knows what Amazon is paying.

Incidentally, Trump is a big fan of paying low taxes in other contexts, as he told Stephanopoulos. “I fight very hard to pay as little tax as possible,” he said, after Stephanopoulos asked about his returns. (One might also note that Trump seems to have some interest in increasing his power in Washington.)

If Trump were to release his tax returns, it would do one thing that Trump has been very good at avoiding for most of his life: pinning him down on how much income he earns, and from where. It would be one of the few times during Trump’s candidacy that we have a hard number against which to evaluate his claims, past and present. How successful his businesses are, what his partnerships look like and so on. We’d have a baseline.

No wonder that doesn’t appeal to Trump.