The main reason for this is that doctors working in the private sector have more incentive to work. Government employees receive the same salary regardless of their input of work; private sector employees receive monetary compensation for going the extra mile or squeezing in that extra patient. That's the magic of capitalism; by allowing the amount work to directly correlate with salary, you create a desire to work harder, smarter, and longer.
Research shows that private health care doctors many times have greater access to more continued education, funding, advanced technology, etc.; however, a public health care physician that does not have that access can indeed use their God-given ability and desire to truly serve people, to aid in the healing process as well. Life experience teaches us that patient, doctor and man's creator are an unmatchable team!
Private health care naturally has the best doctors, because it has more money. Public health care relies on governmental funding and governmental funding for health care is scarce these days. Private health care can afford to pay the best doctors the money they seek and, thus, they are inevitably attracted to private hospitals and practices.
Private health care doctors make a larger salary than public health care workers. They also work for companies that are able to pay for them to attend multiple health conferences and stay up to date on current health news, which is not always the case in the public sector. The best doctor is one that continues to grow over their career, which is easier to do in private health care.
I believe that we have much better health care when we go to doctors who are in private practice. The health co-ops have far too many restrictions on the doctors they hire, and they don't pay those doctors well, so they probably attract the doctors who are either just out of school and need a job, or they can't find jobs elsewhere. With private health care, not a type of "group health care", the doctors are much more motivated to be the best they can be, provide much better service, and are generally more knowledgeable and take better care of their patients.
Even if it tends to work out that way the quality will depend on how the health care program is run. A government could take drastic measures to guarantee quality doctors and then they would be of a better quality.
It's a common misconception that private health care comes with higher educated or more successful doctors. But, studies performed by the World Health Organization indicate the that quality of care in socialized medicine systems is comparable to, or often exceeds, that of privatized health care systems. The educational requirements of doctors under both systems are similar, and compensation is similar, based on experience.