Therefore, one could sign up for Zerocare in the ambulance on the way to the hospital, and care would be covered by insurance.
You can sign up any time you want, but just because an insurance company has to take you as a policy holder doesn't mean that you are covered immediately. They could make you wait several days, weeks, or whenever they're "policy term" dictates. If you don't have insurance when you get in that ambulance, you're not going to have it by the time you get out.
So, good luck with your plan to go without insurance, genius.
Um, well actually, I plan on going without Zerocare because signing up for it will violate my religious beliefs as a Catholic. If you consider someone who objects to Zerocare on religious grounds to be a deadbeat, then so be it. The govt. is forcing our hand on this, but you obviously will do as you are told.