British Prime Minister Theresa May called the election that took place in the U.K. last week because she thought voters would sweep her Conservative government to a much bigger majority in Parliament. Instead, her Conservatives lost seats, the opposition Labour Party (led by an unreconstructed, anti-Western, Marxist) gained 29 seats, and the country ended with a "hung" Parliament.

There is a lesson in May's mistake that applies in America. In fact, the lesson was already taught in the 2016 election. It is simply that the typical voter is not as ideological or policy-focussed as the political class.

May assumed she could take advantage of what appeared to be the unelectability of Labour led by Jeremy Corbyn, the clumsiest and most extreme socialist major-party leader in recent history.

The Tories also thought voters who had previously preferred the U.K. Independence Party would now vote Conservative because UKIP had lost its raison d'etre when the country voted a year ago to leave the European Union. "We've seen those who previously flirted with UKIP move back to the Conservatives in large numbers," political expert James Crouch told the Daily Express shortly after the election was called. "UKIP has seen many of its supporters abandon the party for the Conservatives," the Express wrote in late April. Labour-sympathizing columnist Rod Liddle granted that May would pick up seats "in frowsy, dispossessed towns where UKIP has performed well." The Guardian reported that May had an opportunity "to recruit UKIP voters."

The theory was that Tories last week would scoop up most of the 12.6 percent of voters who had picked UKIP in the 2015 election. UKIP's 2015 manifesto and Labour's in 2017 contained some overlap but plenty of divergence, especially on wasteful government spending and environmental extremism. Labour's manifesto gushes over immigrants, while UKIP's was, too put it mildly, less receptive.

But it was naive to think that most UKIP voters would suddenly become Conservatives. Prime Minister May was an opponent of Brexit while Corbyn had long been openly skeptical of the European Union, which he saw as a mechanism for enriching big business.

Sure enough, UKIP's vote total plummetted from 3.8 million in 2015 to just 594,000 last week. But the 3.2 million voters they lost didn't all go to the Tories. Only one-third of them did. Labour's vote tally grew from 9.3 million in 2015 to 12.9 million in 2017, suggesting they got most former UKIPers plus most new voters.

This is confounding only if you look through an ideological lens. The manifesto with which UKIP won 3.8 million votes was far closer to that of the Tories than to Labour's, and May even stretched her party to the left a bit to win some less conservative voters. But she failed. And the fact that she failed suggests that policy and ideology we not what drove those voters.

Nationalism is part of it. So is populism. And so is the urge to rage against the machine. Americans have regular elections so they don't face unexpected ones called at the whim of a leader in power. But the British experience is that voters don't like being forced to have unnecessary elections, particularly those in which their votes are being taken for granted. They are likely to protest, and that's what they did in Britain last week.

Americans had a similar surprise in 2016. Much of rural America had opted for Mike Huckabee over John McCain in the 2008 primaries, and Rick Santorum over Mitt Romney in 2012. In consequence, analysts and Republican politicians saw these voters as Christian conservatives. Then Trump — thrice-married, recently pro-choice, a New York moderate, and a former Democrat — won them over.

Something other than ideology and policy made this happen. Rep. Thomas Massie, R-Ky., tied the Tea Party and Trump's win together with a single idea, saying, "they were voting for the craziest son of a bitch in the race."

Ideology isn't a bad thing. Often "ideology" means a thoroughly thought-out system of how to govern. Statesmanship involves balancing what one believes is best with what voters say they want. The first step, though, is realizing that these are often different.

It's easy inside the bubble of Capitol Hill or Westminster to make the mistake of assuming voters are mostly ideologically or policy-minded. After Trump and Corbyn, no good politician should repeat this mistake.