I understand the sentiment, but 3% is crazy, wtf? I want to shop at your business if you own a shop somewhere. Would you want to run a business, put in the hard work and only have 3% of profit? And for insurance company, they carry a lot of risk, that 10% profit is only because they made money on investment in combination of not having more big losses. One freak storm will probably be enough to turn that 10% into 5%. (As a comparison, the big 4 banks in Canada makes about 20-30% net profit.)10% profit is a crazy amount in this market. Consider that's AFTER paying wages and overhead; it's literally just extra money...3% would be more reasonable with the economy as it is.
Regardless, the average isn't the issue. Multi vehicle owners are a vast minority, and we get screwed because of it. If we didn't get screwed, we might skew that average profit 0.001%, and we'd be much happier. But of course, 0.001% is still at least a few hundred thousand, and well, they aren't just going to give that up.
I don't know what you mean by multi vehicle getting screwed. If your second car isn't a daily driver, you can insure it as a leisure vehicle which has lower rates than a daily. With additional vehicles on the policy, you can multi product discount. For your project bikes, just shop around, I think some insurance company allows for theft and fire only if you have multiple motorcycles on the policy. Also remember, motorcycle rates are already calculated based on the usage from what I understand. For example, if your insurance is $1200/year, it doesn't mean your premium is rated $100/month, the insurance rate is probably calculated $150/month for 6 riding months, and $50/month for 6 non-riding months. So for some insurance company, they don't allow theft and fire only during off season.