Mark, yes, people without insurance can and do get treatment in hospital emergency rooms -sometimes even for things that aren't immediately life-threatening. But that does not mean that the hospitals don't hit them up for a huge bill afterwards.
If you're truly indigent, the hospital may just write it off as "bad debt," but if you have income and assets but don't have health insurance, for whatever reason, if you go to an emergency room you're going to be billed for the ambulance, treatment, hospital stay, etc. that you used. And that bill could be big enough to bankrupt you.