in reality , the price included the cost of fuel , of accident insurance , of health costs or health insurance required by the waste products produced by the chariots , the risk of having to pay for repairs , medical treatment , and litigation following an accident , the risk of death for ones self or a loved one due to accident , or to war over mana supplies , taxes to build and maintain roads , taxes to maintain a police force to enforce the right-of-way rules , taxes to deal with toxic waste produced by chariots , and so on .