Andrew Warner is in the hospital

They might have insurance --- which is often obtained through the employer, but doesn't have to be. (And which might pay for only certain procedures, or only for doctors and hospitals who have a prior arrangement with the insurance company; also, many policies will pay most of the bill, but not all of it.) Insurance obtained through employers is often a better deal, since the employer is insuring a group.

However, there's nothing yet requiring them to have insurance. (The Obama administration's reform bill will require it, but that provision is not yet in effect, and is already being subjected to court challenges.) If they don't, they're personally on the hook.

And losing access to employer-sponsored healthcare plans is indeed a disincentive to people who might otherwise want to strike out on their own.

Now, he might have straight health insurance. In which case he pays x%. His insurance company may or may not have a deal with the hospital to negotiate a lower rate. In either case Andrew would pay x% of the finial cost up to a certain cost. There may also be a copay he would be responsible for.

If he has an HSA, then he pays everything unto a certain amount typically $3500 - $5,000 and he can put tax advantaged money into what's called an HSA account.

HSA's make sense for young people, 'regular' insurance makes sense for older people or people with lots of health problems.

EDIT: Interesting Side Note...

In America, it is typical to get "This is not a bill" bills. Basically, it is a statement from the hospital that outlines all the expenses, but it states, "This is not a bill" on it. You will then get the real bill from the insurance company, which is typically a lot less. For example, a family friend spent 3 or 4 days in the hospital before she passed away and racked up ~$300,000 in medical expenses. The family ended up paying about $2500 for the medical expenses.