President Trump is not a very popular politician — and there are many reasons why. But one of the biggest is that America just isn't great again yet.

We all know that Trump is unlike regular politicians. But I would suggest that Trump's biggest problem is actually one that most politicians face, which is not caring about the actual policy impact of their decisions.

I don't mean this in a small way. I mean it in a big way. I mean that most politicians care more about how their initiatives will be communicated, and which constituencies they will please, than how it will affect most people.

My point is not to make a moralistic argument about doing the right thing. As the long-established correlation between GDP growth and incumbent re-election shows, voters hire politicians with a very simple mandate: to make their life marginally, but noticeably, better. And they are unsentimental bosses, who hire and fire based on results; they don't take excuses such as the cyclical nature of economic booms and busts.

But most politicians think the way to re-election is to have a good message and brand, and to please enough constituencies. Actually, demonstrably, the way to get re-elected is to make a positive difference in people's lives.

Take Obama's stimulus plan. The goal of the plan was to revive the economy in the depth of a recession by pouring lots of money in. The problem is that for so-called Keynesian stimulus to work, you have to spend all of the money at once — think of it like an electroshock. But to please labor and environmentalist constituencies, Obama made sure his stimulus bill would mostly be spent on public works and pork projects like high-speed rail. What mattered was the idea of the stimulus — being able to pass a big bill with a big price tag and being able to say that he had passed a big bill with a big price tag. The bill actually accomplishing its objectives was secondary. Obama was re-elected, but it was a close-run thing against a formidably weak opponent.

In France, Nicolas Sarkozy was a master of this. The agenda he ran on was very good; the problem was that he just didn't implement it. He lost re-election by a hair, in the context of an economic slump. If he had faced down protests early in his term to implement the kinds of labor market reforms he'd promised and that nearly all economists agree would have helped France, he almost certainly would have been re-elected. His cowardice wasn't just immoral. It was his undoing.

And so now, take the American Health Care Act, the House GOP's ObamaCare replacement bill that Trump is forcefully backing. Trump's goal is political: He wants to be able to take credit for passing a bill that "repeals and replaces" ObamaCare. But he got elected on a very different promise on health care: He said he would build a "great system" that would "cover everyone." The AHCA can't do that because it is designed with parliamentary-political kabuki in mind: It doesn't spend enough money to cover everyone to appease hard-right Republicans; at the same time, it doesn't go deep enough in terms of free-market reforms to actually change the system in a positive way, so as to not to turn off too many moderates.

There is an implicit contempt for voters at work here. The bill assumes that voters are just too dumb to notice its impact and need to be razzled-dazzled by PR. But it also assumes that policy doesn't actually change much. Both those assumptions are mistaken.

I predict we'll see something similar with tax reform. Some changes to the tax code, like payroll tax cuts and child tax credits, can have a major, direct impact on the lives of millions of families and make them measurably better off. And those families will notice, and remember when polling day comes. Other forms of reform won't do that. And yet I predict that politicians will care much more about the abstract Beltway politics of the upcoming tax reform plan than its actual impact.

Trump's penchant for communication and disinterest in policy has been widely noted, but it's just an extreme version of a problem that all politicians have. Indeed, it's almost a cliché that politicians care more about communications than impact. But it's a mistake for politicians to behave like this, not because it's immoral — though it is — but because it is against their self-interest. Policy does have an impact, and people vote on it.