The social contract is really to fix the damage your (at fault) collisions cause. At least in jurisdictions I've been in, the state requires evidence of financ

The social contract is really to fix the damage your (at fault) collisions cause. At least in jurisdictions I've been in, the state requires evidence of financial responsibility as a requirement for driving. (Enforcement is a separate issue from requirement). A car insurance policy is evidence of financial responsibility, and the most common; but you can also post a bond of something like the minimum insurance amounts. Yes, if you don't have the money to post a bond, you're more or less forced into insurance or not driving (or driving illegaly), but that's we know you'll uphold the social construct of fixing the damages you cause. You don't need insurance to ride a bicycle, because it's not as easy to cause damages with a bicycle.