Soldato
The amount of damage a cyclist can do to a car is insignificant when compared to the damage a car can do. That's why there is no compulsory insurance for cyclists as the cost/benefit ratio doesn't make it viable. It's the same reason why horses and pedestrians don't need compulsory insurance to use the roads (and it can be argued that a horse can do more damage than a cyclist).
However, cyclists are free to arrange thier own insurance if they want to.
bang on!