What happens if the other driver fails to inform his insurance after an accident?

I can only speak for Florida because that is where I live and it is a no fault State. In Florida it really would make no difference to you if the other driver did not inform his insurance company of an accident. Really, you would only have to file a claim with your own company and contact his insurance company after the accident. I would just make sure you have the other drivers info so that you can contact them about the accident.