A person's income determines his/her access to many things he wants and needs: food, clothing, transportation, housing, entertainment, and the internet, for example. And people who have higher income are able to consume more of all of these categories than people with lower income, if they choose to. More affluent people shop for food at Papa Joe's or Whole Food; live in larger and more luxurious homes; buy their clothing from boutiques rather than Penny's or the thrift shop; and drive multiple handsome cars. Poor people can't afford the luxury end of these forms of consumption. And in some way our culture has judged that these sorts of inequalities of consumption are a legitimate and fair part of a market economy; if you judge that inequalities of income are justifiable (perhaps with some limits on extremes), then you pretty much have to support the idea of inequalities of consumption as well.
But what about goods that have a price but that are essential to living a decent human life? Food certainly falls in this category; if 30% of society could literally not afford to purchase enough calories to provide 2200-2900 calories per day for adults and 1800 calories for children, then we would probably have a different idea about the fairness of a market for food -- the principle that says "to each according to his/her earning capacity" doesn't seem very convincing in circumstances where it leads to malnutrition or starvation. In other words, if the normal workings of a market economy left a significant segment of the population without the ability to purchase enough food for subsistence, we would surely judge that this isn't a fair or socially just way of distributing income and food. And there is an important point to be noted here: there is hunger in America, and the system of producing goods and income isn't fully satisfying the subsistence needs of the whole population. (This is exactly what makes it compelling that our government needs to provide food assistance for the very poor, through food stamps or targeted income supplements.) So there is an important issue about the justice of current actual distributions of such basic goods as food, clothing, or shelter across the U.S. population.
But push a little deeper and consider the "market for health care". Supporting one's current healthy status is a costly effort; repairing the body in times of traumatic injury or serious illness is even more costly; and our society leaves a lot of the allocation of health care services to private purchasing power. Health insurance is the primary vehicle through which many Americans provide financially for their health care needs. Some people have insurance provided or subsidized through their employers; some families purchase health insurance through the private market; and many families lack health insurance entirely. Upwards on 47 million Americans are uninsured, including 20% of adults and 9% of children (CDC link). And this includes a wide range of Americans, from the extremely poor to the working poor to the solidly middle class.
It is clear that access to doctors, hospitals, nurses, and prescription drugs is a critical need that everyone faces at various points in life. It is obvious as well that one's future ability to live and work productively and to enjoy a satisfying life is conditioned by one's ability to gain access to health care when it is needed. It is also clear that uncertainty about the availability of health care is a major source of anxiety for many, many people in U.S. society today. So it is self-evident that decent health care is one of our most basic and unavoidable needs.
So what do people do when they lack health insurance and serious illness or injury occurs? This isn't a mystery anymore; families go into debt to doctors and hospitals, they face bankruptcy, they find some limited sources of free care (free clinics, pro bono doctors' services), and they forego "optional" treatments that may well extend the length or quality of life. And it is evident that this pattern results in very serious harms and limitations for people in these groups. People who have the least access to health care through our basic institutions may be expected to live shorter lives and to suffer more.
And what about people at the high end of the income spectrum? How do they relate to the problems of health? Here too the answers are fairly well known: they are able to seek out the best (and most expensive) specialists, travel to national centers for specialized treatment, and undergo advanced diagnostic tests that are not covered by insurance. (Here is a news story from CNN on boutique health care.) The affluent aren't able to assure their health through expenditure -- but they can certainly improve their odds.
In other words, ability to pay influences the quality and extent of health care that an individual or family is able to gain access to; and the health status of the family is affected by these variations in quality and access. So, to some meaningful extent, our social system places health care in the category of a market good.
But here is the question I'm working around to: what does justice require when it comes to health care? Is it right to look at health care as just another consumption good like shoes -- affluent people wear Gucci and poor people wear Dollar Store, but everyone has his/her feet covered? Or is health care in a special category, too closely linked to living a full human life to allow it to be distributed so unequally? (Norm Daniels has spent most of his career looking at this issue, from the points of view of philosophy and concrete policy reform. See Just Health: Meeting Health Needs Fairly for some of his findings.)
It seems a bitter but unavoidable truth that there are very substantial inequalities in the provision of health care in our society. One person's likelihood of surviving a devastating cancer may be significantly less than another person's chances, simply based on the second person's ability to pay for premium health care services. Further, it seems unavoidable that these extreme inequalities are flatly unjust in any society that believes in the equal worth of all human beings. And where this seems to lead is to the conclusion that some system of universal health insurance is a fundamental requirement of justice.