The government should NOT have the power to force individuals to do business with certain private companies. I can understand car insurace since driving is a priviledge but mandatory health isurance? Sounds like someone got bought out by the insurance companies.
Collision insurance makes sense because it isn't really for you; it's for anyone you happen to hit. Mandating Uninsured Motorist would be unforgivably paternalistic. Not that carrying tons of UI is a bad idea, mind you.