My wife's grandmother while being treated for cancer last year, was literally taken by ambulance (god only knows why) from one side of the medical campus to a building on the other side (3 minute ride) for around $9K. This is Chicago, so hopefully not typical. :-D

Liability.

Same thing happened to my wife and I asked why I couldn't just put her in a wheelchair and push her across the parking lot. Since she hadn't been discharged, she was still in their care so if anything happened, they would be legally liable. However, either insurance took care of it somehow, or the hospital never charged for it because it didn't show up on the bill.

Yes, and you won't realistically know how much it will be until afterwards, like most things in the US healthcare system. Unfortunately.

Yes, and in many places you won't know what ambulance company will come when you call, and many of them intentionally aren't in-network for many/most insurance plans, because they believe that they get screwed over by the insurance companies. So even if you have insurance (good insurance!), you could get hit with a multi-thousand-dollar bill after a 10-minute ride to the hospital.

It's disgusting.

Yes, and sometimes absolutely ridiculous amounts.

In canada too unless you have private insurance

Varies wildly by location and circumstantial details just like everything else in US healthcare.

Yes, most people are extremely hesitant to do so, because of the probable high costs.

You'd be shocked at the condition in which people will drive themselves to the emergency department.