In fact, a report in Governing points out that, according to the latest data from the federal Survey of Consumer Finances, that bottom 80 percent has had, at best, flat retirement savings.

Says the report, "Vast disparities are also found across demographic groups," adding that "[w]hen the average liquid retirement savings of white families is compared with that of African-Americans and Hispanics, the gap has widened fivefold over the past 25 years, according to the Urban Institute. Young people, too, haven't amassed the same wealth their parents did at comparable ages."

According to Signe-Mary McKernan at the Urban Institute, savings and wealth discrepancies are more critical than the more-often-discussed income inequality. She's cited in the report saying that according to one measure, racial wealth inequality, or assets minus debts, is actually three times worse than income inequality.

Disadvantaged groups are less likely to own homes, and many aren't offered retirement plans at work, either—or they participate less frequently.

And that can cause big problems down the line, not just for those with little retirement savings, but also for governments.

Inadequate retirement savings create a growing contingent of residents who have to rely on government services or who might, for instance, miss property tax payments because they can't pay other bills. "It matters not only for families and individuals, but for their cities and communities," McKernan says in the report.

Considering that approximately half of private-sector workers aren't offered retirement plans by their bosses—with those workers frequently in low-income jobs or working for small companies reluctant to go to the administrative expense of providing a retirement plan—some states have started tackling the issue on their own, even despite the Trump administration's efforts to stop them by rolling back an Obama-era regulation to make it easier for them to do so.

Oregon currently leads the pack, with a plan that started its rollout last year. In fact, its plan is working better than the late and probably unlamented myRA, a federal program that failed to auto enroll participants. Oregon's plan does conduct auto-enrollment, and about 70 percent of workers have remained in the program instead of opting out.

Currently, according to the Pew Charitable Trusts, nine states have enacted legislation to offer the planless a way to save for retirement.

More states are expected to launch their own programs, and absent action from the federal government, that may be the way forward for those with no other way to save.