A quick first point: you're making a blanket statement against a heterogeneous population. Some non-profits are definitely not efficient, and some are very efficient.
The big difference, and there is one, is related to ownership and operations. There are no distributable earnings, and they cannot be sold/acquired. This definitely factors into decisions balancing profitablity and ethics. There are laws about nonprofit compensation, too: https://www.guidestar.org/ViewCmsFile.aspx?ContentID=3890
I am not a physician at a non-profit! But I had read a few years of Tenet and HCA annual reports a while back, and have a few other points of exposure to non-profit vs teaching vs private systems. Perhaps we can agree that there are many opportunities to improve the system in many ways.
The big difference, and there is one, is related to ownership and operations. There are no distributable earnings, and they cannot be sold/acquired. This definitely factors into decisions balancing profitablity and ethics. There are laws about nonprofit compensation, too: https://www.guidestar.org/ViewCmsFile.aspx?ContentID=3890