Well for one Obamacare may mandate that people have health insurance but it does not mean everyone actually has it, likewise your car insurance may not cover personal injury for you or someone else as mine doesn't. Secondly while its certainly possible that someone may be able to pay for post-accident healthcare out of pocket, there's no denying the large numbers of people who either can't do that or who suffer from such horrible injuries that the costs are beyond what a typical household could cover. Obviously when I mention the ER costing tax dollars I'm not talking about the people who don't cost tax dollars from their treatment. Thirdly, all hospitals and state/county/municipal governments run analysis on trends to determine the best numbers for things like number of EMTs, ambulances, doctors, nurses, beds, specialized equipment, etc, etc, etc. If less people wear seat belts then these numbers increase and the local government is either forced to expand its local emergency care system, more EMTs, more ambulances, etc all which of course cost tax dollars, or provide less care or lower quality care. Lastly, in any insurance system the more people drawing money from the system increases the demand for money going into the system, simply put the more people who draw money out of the big pool of cash that is the result of all your insurance payments, the more in payments that pool needs to stay viable, in other words the more people that get into accidents who share the same insurance providers as yourself mean you will eventually start paying higher rates or seeing less coverage.
Wear your damn seat belt.
