Yeah I see what you're saying, but I think this is an unproven theory considering the relative low cost of healthcare elsewhere. It's not as if covering everyone in the country is the only thing that changes in terms of healthcare dynamics. Think of the give and take.
Lets theorize:
- We could possibly have more patients and less emergency cases, since prevention is not expensive anymore so less people wait until things get out of hand and they're lying on an operation table or something. That can easily lower healthcare costs.
- With the focus being around healthcare instead of funds and expenses in public hospitals, the administrative costs of healthcare can significantly drop, saving hospitals millions if not billions every year. Also with that kind of focus, the quality of healthcare might actually improve - not in terms of professionals, but the end results of having less administrative complexity and more direct treatment with less ties to financial issues - so everyone could reap these indirect benefits of universal healthcare that places such as Sweden (number 1 in health care in the civilized world) and Canada.
This is all theory, other nations are doing great with it, and the rich people still travel around and pay for special treatment at private ones so they can skip waiting in line with the less wealthy.
Also, imho, the reason congress is not moving anywhere with healthcare is because they have to be careful not to step on too many toes or they lose the support of this or that lobby that's helping fund political campaigns. In a sense, the interests of the lobbies and special interests are what politicians are looking after, not the general public, realistically speaking. Sometimes the two interests don't go hand in hand, and the public is not as organized/coherent as a lobby with unified funds and agendas.
This would probably be the biggest obstacle to universla health care, insurance companies that make a killing off of the current system would never have it, that's for sure, but the public itself can be receptive to the idea (%75 figure quoted). In the end, politicians will do what's in their interests or get replaced by ones that are more in line with political forces' demands.