By the numbers: Sandy Baum and Alexandra Tilsley at the Urban Institute estimate that more than a third of the total subsidies required for universal free public college would flow to students from families earning $120,000 or more, who already tend to enjoy better K-12 educations.

Ms. Baum and Ms. Tilsley write in The Washington Post:

A national free-tuition plan would provide disproportionate benefits to the relatively affluent while leaving many low- and moderate-income students struggling to complete the college degrees that many jobs now demand . Ironically, free-tuition programs would exacerbate inequality even as they promise to level the playing field. … A progressive educational policy should offer much more narrowly targeted help for students.

Related:

Higher education is a public good, and public goods should be universal

Supporters of free tuition say that talking points about free-riding “millionaires and billionaires” are misleading — not least because millionaires and billionaires are far less likely to send their children to public universities.

A different crunch of the numbers: Mike Konczal, a fellow at the Roosevelt Institute, estimates that families within the top 1 percent of the income distribution would capture 1.4 percent of total spending on free college — slightly regressive in relative terms, but arguably not an exorbitant price to pay for the 98.6 percent of spending that would benefit everyone else. And crucially, supporters say, under the Sanders and Warren plans, that spending would be financed by raising taxes on the rich.

But Jordan Weissman contends in Slate that to quibble about the relative progressivity of different college tuition funding proposals is largely to miss the point. For many proponents, universal free public college is part of a broader political vision to establish higher education as a public good that everyone buys into, like the fire department or library.

He writes:

The entire policy agenda of the social-Democratic left is based on the idea that simple, universal government programs are generally better than means-tested benefits, because letting everybody enjoy nice things like higher education for free or cheap creates buy-in for a robust welfare state, whereas programs for the poor are easily targeted for cuts.

Representative Alexandria Ocasio-Cortez of New York pursued this line of thought in a Twitter thread: