For one thing, they tend to have much higher administrative costs than publicly run health care programs. See, for example, Wikipedia's article on health care in the US: http://en.wikipedia.org/wiki/Health_care_in_the_United_State... or this blog post by Ezra Klein: http://voices.washingtonpost.com/ezra-klein/2009/07/administ...
There are also all the reasons cited in Krugman's post.
Then there's the fact that the U.S. spends about twice as much on health care as any other developed nation and gets results that aren't clearly better overall. Is it a coincidence that we have the largest component of private spending?
If the insurance companies aren't already good at spending money on health care, what makes anyone think that if you give them the whole system to run, it will be any better?
Just a reminder: http://www.gallup.com/poll/102934/majority-americans-satisfi... - instead of working at the people who aren't satisfied with their insurance or don't have any, we'd rather create an entirely new system from scratch?
As for higher administrative costs, as a number cruncher and one who has worked with non profits, this number can be both juiced and reduced depending on the operational strategy that's taken. For instance, despite higher administrative expenses, medicare fraud (15+%) is thought to be considerably higher than private healthcare - so there's a trade off here between administration and waste elsewhere. I'm not saying that this is necessarily the case here but given the fraud numbers, that case does seem compelling.
I'm not fond of the US insurance industry as a whole given that it's all third party payors (ie your employer chooses your insurance, not you) which introduces all sorts of wacky results but I find it odd that they wouldn't rather give users of the system more power rather than centralizing it with governments. Again - look at the stunning er, competence with which the bail out package has been run.
also fyi - http://www.washingtonpost.com/wp-dyn/content/linkset/2005/07...
update - apparently administrative costs are higher not lower for Medicare than private insurance, check this link out: http://www.heritage.org/research/healthcare/wm2505.cfm
Is anybody talking about a plan like that? I haven't heard anything about it, and I would think the GOP would be touting it if thats what they wanted. Most republicans I've heard either seem to be for inaction or for a health care bill that doesn't do anything for the uninsured/needy
Administrative percentages are lower for medicaid than for private insurance mainly because people on public insurance spend a lot more medical dollars than those covered by the private sector. Since administrative costs usually tie to recipient, you have less recipients receiving more money, driving down percentages.