I had to look that up. I found this:
The Scandinavian countries are the EU average, Denmark is a little below and the others a little above the average which is 3.04 physicians per thousand people, for the US the number is 2.3 physicians per thousand people. Ie. about a third more, but there is more to it only it is hard to put numbers on.
I work in eHealth so I know a good deal of people that in the medical field, including some which have personal knowledge on how things are done in the US. There are two factors which influences what the physicians gets done, which means physicians spend much more on each patient so they handle less patients.
The first is that in the US there is a lot of whats called defensive medicine ie. doctors and hospitals are doing a lot of rarely needed procedures to ensure they will not get sued by patients for having missed something. This is not only very costly, but it of course means even simple things take longer.
The second is that, and I do not know it this is true for nurses in all EU countries or just here, our nursing staff here do more advance stuff than in the US - supposedly nurses here are simply trained more/different so that enables them for the more advanced jobs. The result is that nurses here handle things that only physicians do in the US, so again less to do for physicians here for each patient.