Health policy analysts have long been puzzled that millions of uninsured people snub the government’s offer of free health benefits. The Kaiser Family Foundation estimates that seven million of the 27.5 million nonelderly people who were uninsured in 2016 were eligible for Medicaid. That’s more than one-fourth of the uninsured population. Another eight million were eligible for Obamacare premium subsidies, meaning that more than half the nonelderly uninsured didn’t avail themselves of government-subsidized health coverage.

Academic research suggests one possible reason: Medicaid recipients aren’t the primary beneficiaries of the program’s spending.