To call a spade, a spade, the insurers always win - that's life, unfortunitely, but they are a "necessary evil".
Getting back to the cyclist, and their need for insurance to cover public liability, and the option of persinal liability, I think there's a couple of influencing factors to consider:
- there are more people cycling these days, with more people also being encouraged to cycle, which increases both the risk, and the likely number of incidents, going forward.
- there's no mandatory training, testing, or licensing, for cyclists. Literally anyone can get on a bike without relevant safety training etc.
- cyclists have the ability to travel faster than pedestrians, so if they hit something /someone, then the impact will likely do greater damage, than say a pedestrian / runner, colliding with another person, or piece of property.
- There's also the additional consideration that in a collision, part of the bike might do damage, or inflict injury (some pedals claw type grips, some handle bars are pertruding so might stuck in someone etc.)
Is the risks are deemed low, then the associated insurance premiums should be relatively low. Perhaps the fact that insurance isn't mandatory, and there's very low take up, results in little or no competition from insurers, so those in the market can charge what they like etc.?