Many industries are regulated and have to provide good faith justifications for price increases. The burden of proof is on them, not the service recipient.

Or cut expenses, educate the insured on safer behavior, ...

And not just a bit. Insurances have lost money for most of the last 5/6 years.

They are not all losing money.

And yet there's seems to always been enough money for stock buybacks and disgustingly excessive executive compensation.

Insurance in general is more heavily regulated than this. There are a few reasons: because society doesn't want these companies racing to the bottom on price and leaving their customers high and dry when the catastrophe does hit, because society finds insurance pricing based on certain personal aspects, such as race, odious, and because the government mandates some types of coverage and they don't want to let insurers rinse customers that are forced to buy their product.

For all these reasons, insurers typically must justify rate increases.