Motor Insurance, like many things in the US, is unnecessarily complicated.
In the UK, it typically breaks down in to three levels of coverage:
Third Party (mandatory for all drivers)
Third Party, fire and theft (coverage as the name suggests - pretty rare)
Comprehensive (covers you for everything)
That's it - that's all your choices. There's no questions about the level of coverage you require for each type of hazard, no questions of under-insured / uninsured coverage etc. There's no chance of being over-insured because the companies are being deliberately vague about what each coverage covers. Its all just simpler.
If you drive for a year, you get a no-claims-discount on your following year's premium. You can accumulate up to about 8 years worth of no claims discount worth up to about a 60% reduction. This is transferable between companies. Allstate has just stolen the idea.