Also, health care is ineluctably two things: a vital necessity and a commercial service. With a single payer, the commercial service objective is warped: patients and doctors are motivated to make care decisions that are inefficient or even harmful, and customer service or premium care for people who want it is eliminated.
Finally, from a philosophical perspective, single-payer implies that the government sets rates for care. Health care is not a natural resource; we don't sell land rights to extract health care to people who drill for it. Doctors spend years and years driving themselves into debt to become care providers, and drug companies sink billions into research for pharmaceuticals. The market for health services is fucking gigantic. It is legitimately daunting to consider replacing that market with a command economy!
I am pro-public-option. But don't pretend that Republicans, conservatives, libertarians, and people who understand health care economics are crazy or corrupted for opposing single-payer.