In addition to what everyone else said, property damage is a big part of it as well.

Let's say you run into a building and knock out a load bearing wall. Or plough through a business or government office. It's not impossible to rack up a couple million in damages if you crash bad enough.

Real answer: in most other countries you can be punitively sued, ex: if a person wants to recoup the emotional damages from being crippled. You can also, depending on the country, be made to cover the cost of services provided by the medical system if you were found to be at fault (I don't know how often that happens for an individual vs. a large company, but that's how the rates were explained to me by a UK colleague)

Repair costs for two vehicles outside the US is probably just as expensive as a doctor's visit for a single person inside the US.

##ItsAScam

Third party liability for my policy is a few million last time I checked, if you somehow cause a heavy truck to crash or damage a piece of infrastructure you can run into those figures pretty fast.