- While it's heart-warming, it is unrealistic to think that a public program can spend infinite amounts of money on citizens who a) have paid "little or no" taxes and b) "throat cancer suffers who quit smoking four years afterwards". The math just doesn't add up.
- The fact that the US has a pseudo market-based healthcare system is what allows drug / device companies to make money on innovations that ultimately save lives in other countries (like the UK) where these drugs / devices may not even break even. If you create a system in the US where it's impossible to make money in healthcare innovation, we'll see far fewer technological developments in healthcare, which will lead to worldwide increases in infant mortality / decreases in life expectancy.
That said, we should have a way in the US to provide basic healthcare for the uninsured. The answer is not, however, a single-payer system.