I doubt ambulances flee from the people without an insurance, no, I just think that they won't actually be getting much more than the first-aid kit. I don't think they'd get a pacemaker or AIDS meds. And I know for a fact that people have been refused meds not on an insurance company's list of approved meds. I don't think you have to look further than the board for examples.
Now, I'm not saying that people here are getting all the meds they need, but I do think people here have a better chance of survival, generally speaking, and I have the statistics to back that up with.