I was once rear ended at a red light. I was knocked unconscious and the driver drove off. A few kind witnesses called police who took a report. They got half his plate imprinted on my bumper, but never tracked him down. I had State Farm, and I was even paying extra for the "uninsured driver coverage". They said they couldn't cover it because until they had another driver's information I was automatically at fault, even with the police report and witness accounts. They said it didn't count as uninsured driver because it's possible the guy had insurance. I was flabbergasted.
In the end I had a concussion and needed to take time off work for recovery and my short term disability insurance ended up suing State Farm because they didn't want to pay for my medical treatment. State Farm agreed to cover medical care but only if it was recorded as my fault and I paid my deductible. In anger I tried to switch insurance companies but found out they have a shared database and since it was recorded as a hit and run my fault, nobody else would take me. And State Farm jacked my rate up 30%...
Some Googling doesn't yield great answers but looks like Poland, Australia, India are the main ones supplying the USA. China makes a lot for itself too.