Earlier this month, Melinda and Bill Gates’s annual letter said they’d been looking to identify areas in which they could expand their philanthropic work in the US. To do so, Bill explained, they took a tour across the country.

Although we travel extensively to learn about the lives of poor people in other countries, we’ve done less of that in America. So last fall, we took a trip to the South to learn more. In Atlanta, we met a single mom who told us a heartbreaking story about how she had just been evicted from her apartment for missing a rent payment while in the hospital with her newborn son. We had coffee with a few residents of an apartment complex in one of the city’s poorest neighborhoods. They showed us mold growing on the walls and ceiling of one of their homes. They told us they routinely hide their children under a bed or in the bathtub because of the sound of gunfire. It would be an understatement to say the people we met in Atlanta faced big challenges. But they were also incredibly resilient. At a Boys and Girls Club, we met a man who uses his own money to buy lunch for the kids. We talked with former prison inmates who are now holding down jobs and raising families.

What they saw on this trip, they say, “reinforced the importance of education,” “made us think” and “certainly had an effect on us.”

Their tour of poor America sounds not unlike Mark Zuckerberg’s 2017 tour of the US. In January 2017, Zuckerberg had announced his yearly challenge as one in which he would visit people in every state, meeting with local communities and learning about the lives of his fellow Americans. He visited farms, trail parks, inner cities. Overall, most of the places he visited were home to communities who earned less than the average American—and many of them outright poor.

But Zuckerberg didn’t need to go to rural Ohio, or visit communities in Mississippi, to assess the staggering lack of opportunities within his country: A stroll to Facebook’s cafeteria, whose workers are forced to live with their families in garages, would have sufficed. And since Seattle ranks second behind San Francisco in income inequality, it’s likely that the Gates too could have found pockets of disenfranchisement in their own backyard.

Perhaps they didn’t know that they were there. As a recent UN report shows, America’s poor are deeply isolated and kept at a distance not just from the very rich, but from the moderately comfortable. US inequality isn’t a simple divide between urban and rural; even poor people who live and work next door are rendered invisible by the structure of American life.

America is an unusually unequal country, and ranks far behind other rich nations in all measurements of inequality. The country’s lack of welfare and shared services—such as high-quality public education, government health care, and public transportation—keep citizens from moving up and down the income ladder. They also keep citizens from intersecting socially.

In countries that invest in welfare, where public services are often superior to private services, wealthy and middle class citizens mix with the working class to use them. In Europe, for instance, all of the top universities are public, and have typically cost much less than even America’s state universities. The same is true for Europe’s highest quality hospitals, which are covered by socialized health care.

In December 2017, New York University law professor and United Nations consultant Philip Alston spent two weeks investigating poverty in the US. His report describes a parallel universe nested within the wealthiest nation of the world, one troubled by homelessness, debt, lack of sanitation, sickness, destitution, drug addiction, and environmental hazards. Across the country, Alston adds, he found himself confronted by “contrasts between private wealth and public squalor.” Alston cites the World Inequality Report 2018, noting that “in Europe and the US the top 1% of adults earned around 10% of national income in 1980. In Europe that has risen today to 12%, but in the US it has reached 20%.”

Of all the solutions to poverty that other developed countries have already implemented, Alston points out one particularly American failure: Insufficient public services and structural support for lower income people. Describing the American view of welfare services, Alston notes that in the US society “immense faith is placed in the goodwill and altruism of the corporate beneficiaries, while with welfare reform the opposite assumptions apply. The poor are inherently lazy, dishonest, and care only about their own interests.” As he notes in his report, the tax reform and the policies of the Trump administration are only likely to expand that divide.

In other developed nations, it is not the wealthy’s responsibility to fix social problems beyond paying their taxes, it’s the government’s. There, health care, education, sanitation, transportation, and prisons are basic services before they are goods; research shows that when those services are privatized, they fail the underprivileged and continue to keep them separate.