I'm sure I've written about this before, and I'm sure I'll write about this again, but car insurance is just *different* between California and Northern Ireland.
One difference is who is insured to drive: in NI, the only people insured to drive your car are the people specifically listed on the insurance policy. If your spouse isn't listed, they're probably not insured in NI.
California is different: basically anybody who has your permission to drive your car is insured. Also, family members are insured even if they don't have your permission. (At least, as far as I can tell!) This is better.
Another difference is what you're insured to drive. In NI, if you have comprehensive cover, then you're probably insured to drive other people's cars third-party-only. (That is: if you crash their car, you might have to buy them a new car.) If you only have third-party insurance in NI, then you probably aren't insured to drive other cars.
If you hire a car in the USA, interestingly, it seems that you don't need to take out insurance from the hire company: your normal car insurance covers you. Let's just say that this doesn't happen in NI.
Another cool thing about California: my insurance policy says something like "if you buy another car, and all your cars are currently insured with us, then you get thirty days insurance on the new car until you have to tell us about it."
Another difference is that in NI, if your insurance premiums scale quickly with the "powerfulness" of your car. What's that? You've got a three litre V6? And you're under forty? Ffffffff, s'gonnacostya.
In California, it seems that engine size and powerfulness have little impact on insurance. I mean, I imagine a Corvette is more expensive to insure than a Civic, but it's nowhere near as extreme as in NI (where there could easily be an extra zero!)
One good thing about NI (at least, I *think* it's good) is coverage: insurance basically has infinite liability to third parties. I mean, it's usually a couple of million pounds' limit. Or thereabouts. So basically infinite. Once you have insurance, you're *insured*. Done.
California, not so much. The legally required minimum of third party liability is $35k. So if you cause an accident and somebody needs to spend some time in hospital, and/or they have a nice car, then you're in trouble. Most people with something to lose get higher third party liability coverage!
I have a suspicion, that if you wanted e.g. $2m of third party liability coverage, then the extremes of premium that are more common in NI could start to appear in California. That is, maybe premiums are so closely clustered here because whether you're in a Toyota Corolla or a Nissan Supra, you're about equally likely to cause $30k of damage. But maybe you're much more likely to cause $1m of damage in the faster car. I don't know.
More of the same on insurance later...