I don't think that someone deserves to die or suffer permanent damage because people like you or me decide that they're not making a sufficient contribution to society. There are other pressures on people who refuse to work, and I seriously doubt that the people who absolutely refuse to do anything would make up a proportion of hospital patients significant enough to be a serious issue.

And in any case, taxpayers are already paying for indigents that can't afford -- or are ineligible for -- proper health insurance; the difference is that we're paying for it when whatever problem they have becomes life-threatening and they have to go to the ER, which is much more expensive than seeing a doctor and getting preventative care before that point. Universal health care would allow people to see a doctor about things sooner, and thus keep costs down.

As for welfare mothers -- I know they exist, but again, I doubt there's enough of them to be a serious drain on the system. And there are ways to deal with the problem if it does.

In the final analysis, I think the problems you mention aren't big enough to warrant not having single-payer universal health care. On the whole, it will do much more good than harm.