Not inane. Mostly, it's statistics.
There's an entire field of study devoted to risk assessment for insurance. Basically, if enough statistics show a given behavior or characteristic increases risk, it's usually enough to tweak rates. Actual cause and effect isn't always necessary.
Statistic show smokers have higher rates of auto accidents. If you quit smoking for a year, most insurance companies will be glad to re-evaluate you.
Our car insurance rates have changed a lot over the years depending on our kids' ages, accident records, years we've been driving, school grades, and other things.