Jul 8, 2016 5:00 AM EDT Trending  By John Wasik / MoneyWatch  On its face, Hillary Clinton's recently proposed plan to cover college bills looks like a shiny new car -- until you look under the hood and wonder how it will run.  As with most political gestures -- this one a huge nod to Senator Bernie Sanders and his young supporters -- key details are always lacking as to how the candidate will pay for such an ambitious plan.  Then there's the underlying crisis itself. Yes, college costs too much, and more than 40 million Americans have racked up more than $1.2 trillion in debt paying for it. That's not fair, and the country should be heading toward debt-free degrees. But it's not clear if Clinton's proposal will address why so many end up owing so much.  Here are the two major pieces of her plan, according to her campaign website: Families with incomes up to $125,000 a year will pay no tuition at in-state public colleges and universities. The plan will be phased in over five years, but families making $85,000 or less will immediately be exempt from tuition at in-state public schools. Pell Grants for low-income students will also be expanded.  Although Clinton's plan makes no mention of whether it would cover room, board and other fees, her campaign estimates that the program, if implemented, would cover some 80 percent of American families.  What about those already paying on student loans? A third proposal, which could be mandated through an executive order, would give student borrowers a "three-month moratorium on their student loan payments," during which time the government could help graduates either refinance, consolidate or enter into an income-based repayment program.  Moving borrowers into more-lenient repayment programs is generally a solid idea. It should be done now and be automatic for all graduates, most of whom don't know about the nine separate federal repayment options.  The blanket coverage of state college bills, though, glosses over some troubling realities.  College students often struggle academically with classes as well as expenses and don't graduate in four years. That runs up the tab on their total borrowing. When you consider that room, board and fees cost at least $10,000 a year, the additional loans can be a crippling financial burden.  Although the reasons most students don't graduate on time are complicated, many of them simply aren't prepared for college work, are hobbled by the debt burden, have to work or don't get the support they need from high schools or colleges to succeed.  Less than 20 percent of students attending a four-year college get a bachelor's degree on time. The rate climbs to slightly more than one-third for "flagship" four-year schools that are research institutions, according to a report by Complete College America, a nonprofit alliance of 35 states focused on college success.  Completion rates for two-year colleges are even worse: Only 4 percent of students graduate on time, the group found. Not surprisingly, government statistics now look at graduation rates within a six-year time frame.  How costly is not graduating on time? Complete College America found that it runs an additional $16,000 a year for two-year degrees and nearly $23,000 annually at four-year colleges. In addition, lost wages among those still in school and not working adds some $35,000 to $45,000 a year in foregone income.  "Hands down, our best strategy is to make college more affordable and a sure way to boost graduation rates overall is to ensure that many more students graduate on time," said the Complete College America study, entitled the "Four Year Myth."  Unfortunately, only 50 of the 580 public colleges surveyed had on-time graduate rates above 50 percent for their full-time students. That's unacceptable, although the Clinton campaign makes no mention of that uncomfortable fact or the need for all colleges to become more affordable across the board.  Why should public colleges receive a federal subsidy for what would be considered substandard performance in any industry?  Would you be willing to buy a car or appliance from a manufacturer in which less than half of what it produced was ready for the marketplace? I know that may be an unfair comparison, but it raises the question of whether our institutions are doing a competent job in providing a pragmatic, general education.  No doubt, college costs too much in an age in which a degree doesn't guarantee you a decent job upon graduation and the resulting debt prevents you from buying a home or car and raising a family. It's a societal malady that needs be examined closely.  Yet it's negligent to cover the cost of college without tackling the question of how to provide better college preparation and addressing the demands of a globalized economy. The best high schools are already doing this through advanced college courses, quality teaching and counseling. Many, though, are still coming up short on basic language and math skills.  Unless more accountability for graduation rates is introduced, the high cost of not getting a degree will continue to haunt Americans. They'll keep struggling to get educated for a workplace that has become ever more demanding.
Moving toward a debt-free degree is a good start, but her campaign promise may ignore serious underlying problems