But then every negative externality not taxed is subsidized. It dilutes the meaning of subsidy because with this new definition government accounting doesn't m

But then every negative externality not taxed is subsidized. It dilutes the meaning of subsidy because with this new definition government accounting doesn't make sense - the government is 'paying' trillions to subsidize all kinds of negative externalities (but it never actually does). Also, if the government actually subsidizes a negative externality, you're in a thicket, since some of it is a real subsidy and some of it is the estimated negative externality subsidy.