You have to pay insurance for your car because if you hit someone, not force someone to hit someone, you can likely kill them. This is not true with a bike. Apples and oranges.
A car is a deadly weapon, far deadlier than a gun.
And if a cyclist spills his bike or pulls out in front of a car and the car swerves into a pole/another car/etc.? It can be just as lethal. Again, I'm not saying it's likely, but it can, and does happen .. however infrequently.