1.  Very few treatments are tested against each other to evaluate their relative efficacy.  Even fewer are tested long enough to find out if they actually improve health or prolong life.  Drugs, the only treatments systematically tested are tested against placebos, not against each other.  we have no way of knowing if one is better than another.

-  Worse tests are not long enough to determine if the drug improves health.  The tests are not long enough.  It takes years to determine that.  Instead, reducing blood sugar levels, cholesteral levels, etc. are the results looked at.  But there are numerous effects of any drug.  Until there are long-term studies evaluating improvements in functioning or mortality, there is no way to know which treatment is "best".

-  And this is for drugs, which are tested.  Medical devices (artificial joints, stents, you name it) are not even tested.  Nor are new (or old) surgical procedures.

-  So how do you decide what to pay for?

2.  Medical imaging procedures (CAT scans, MRIs) might be considered "preventive".  But they are expensive, overused and controversial.  Specifically, they may not be needed, and there is a significant danger that they produce numerous "false positives", finding evidence of disease that is not there.  That leads to more expensive and risky tests and procedures to look for non-existent disease.  Do you really want to cover all "preventive" procedures.

3.  Where is your evidence that the US population is so much more unhealthy than the populations of all European nations.  I believe there is evidence of wide variation in health status among those nations.

4.  Think hard about excluding immigrants.  Do you really want millions of people in this nation lacking treatment for communicable diseases, dying of cancer for lack of treatment, etc., etc.  

covers non-citizens. Once while I was on vacation I was in an accident and ended up in the hospital in the UK for 2 weeks and it didn't cost me a dime, the entire cost was covered by the United Kingdom's national health care system.

I believe the same applies for France's health care system also because my sister was once hospitalized in France because of a burst appendix while vacationing at no cost to her.