What if it isn't actually a free market?
Secondly, the reasonablity or unreasonability of payouts is linked to premiums.
In other words, one way that the parsimonious insurer would still have customers is that they offer low premiums compared to the liberal insurers.
Even people who know about the bad anecdotes from reading online reviews will brush that aside for the better deal. (Hey, reviews are biased toward negativity and miss the other side of the story; chances are that wouldn't happen to me.)
The free market doesn't optimize for quality. Firstly, it optimizes for the lowest price for a given level of quality. But the price optimization has a second-order effect of a downward pressure on quality.
If you're selling something and the margin is optimized: it's about as cheap as can be, what you can do is reduce quality by some epsilon, and make a corresponding decrease in price. It still looks like about the same quality to someone not using a magnifying glass and fine-toothed comb, and you have temporary price edge against competitors. That triggers a kind of "gradient descent" of declining quality which bottoms out at some minimum level of quality below which viability starts to get eroded past a point where the market still finds the thing acceptable.