However, if your in-network doctor sends your bloodwork out to a lab that is not in-network, you're now paying a lot more.

Or (until recently), you go in for surgery where the surgeon is covered, but then get billed for an out-of-network doctor that consulted without anyone asking you.

One of the recent situations that I've heard about are nurse practitioners and doctors at your doctor's practice, contracted by your in-network doctor. The person who comes into the room to ask you what you're there about may not be in-network even though the ostensible doctor-in-charge is.

I haven't seen that lab issue. I suppose that could be an issue in specific circumstances.

How am I supposed to do that in the back of an ambulance?

You can't. You should select a plan that covers you at all the local hospitals. If you look it up before hand you can usually specify which hospital you want to go to from memory. I do this not just for the network, but also for quality.

What if you're injured while visiting a different city?

Then you should do research before going or accept that it is an unlikely scenario. This is what people do when travelling, especially internationally. You can also select a plan with the most extensive network to reduce the likelihood.

>In the current system you walk in and hand them your card (insurance, Medicare, medicaid, etc) and they treat you. You get mailed a bill later.

I'm glad we now agree that the current system in the USA is in no way like this.