Like the liklihood that a claim will be filed on a loss. Like the average size of claims. Like the likelihood that a claim will have to be paid at all.

Also, the less competition that segment has felt, the less likely the companies will sweat bullets trying to get all risk accounted for. If all you have to do is put your company's name in the yellow pages to get customers, then they are more likely to keep things simple.

Tradition plays a part too: if the companies serving a market all do business a certain way, then any individual company can do ok by following that tradition. If some whippersnapper comes along and finds a way to use statistics to get a lot of sailers to switch to their company, then the whole market will tend to get competitive in a hurry.

Some companies with major name recognition and loyalty (in auto insurance, think Allstate or Auto Club) may have enough customers who won't switch, that they won't have to get as competitive as others in the market.