Nor should it strive to be a market. Healthy markets can only exist where demand is elastic. If the choice is between dying to kidney failure or enduring life-crushing medical debt, you bet I'm going to do anything it takes to get that transplant. And therein lies the problem: You *cannot* have healthy markets in healthcare. Period. Demand for healthcare is fully inelastic. Anyone arguing the opposite is either profiting off the status quo or woefully ignorant of economics.
I think this is actually an opposite problem. For kidney failure in particular, you can check the insane amount USG spends on end stage care. The demand for healthcare at the limit exceeds any reasonable supply. Healthcare spending across counties goes up pretty much with disposable income. There are massively expensive interventions that could give someone close to death few extra months.
Healthcare has to be rationed. Rationing by market is the least bad kind of we learn anything from history... Too bad healthcare in the US is not a market in any way or form, and in fact the most expensive least DALY efficient interventions (Medicare) are subsidized at the expense of everything else.