Its true healthcare has less frequency so you cant be a sophisticated consumer: but its more frequent than a car, which is also a necessity in many cases, and the lack of sophistry does not make it an inefficient market.
Im not even sure healthcare is a special market, certainly not for infrequency, or because you must pay with your life (i.e. that you make a decision of life and death for resources). Not for restrictive application of labor (lawyers have that), not for the high costs of technology in its application (consumer tech? space exploration?).
I think at this point what makes the healthcare market unique is the common belief of the people that it is unique. It forces the consumer to consciously think of the cost of life, a question we are somehow bred all our lives to hate to ask, but that we answer every day unconsciously.