I guess I'll be the knob... since I handle homeowners claims.
First you need to know that every state has different laws about insurance. Some areas have different laws about insurance. SO the insurance co has to write policies that are in accordance with the laws where you are. I live in Illinois and my insurance {even with the same company} is not going to be the same in Wisconsin because of the laws of each state.
Second, the rates are based on the claims experience of the company in that area. So if you live in an area where everyone turns in claim frequently, then your rates will be much higher than areas where people don't tend to turn in alot of claims. This can change drastically from one town to the next or one PART of town to the next depending on the size of the town {ie Chicago, New York}.
Third, in order for insurance to work at all, you need 10's of thousands of people to pay in in order to pay for a single fire. In the last couple of weeks I have had 2 fires in an area that cover just 5 zipcodes in Chicago. We are talkin about an area that is less than 3 miles by 8 miles. Both of those fires will cost more than $150,000 each. On average, my 5 zipcodes will have 1 of these fires a month. That's 1.8 million dollars in my area alone. That's 3600 people paying $500 per year every year and not getting anything in return. That's just fires. Every day we pay for toilet overflows, baseball thru the window, car hitting the garage door, frozen pipes etc. And none of that includes the occasional windstorm or hail or flood.
So when an insurers see that one kid breaking his neck on an ATV or trampouline is going to cost $500,000.00 each, and anyone can get one for cheap, it makes a little more sense that they don't want the risk. If the rates doubled for 3600 people so each year 3 kids could get hurt on ATV's or jumping on a trampouline, people would be outraged. It's easier and cheaper to just not insure the relatively few who have 'em.