The military and emergency response fit pretty well under the umbrella of things the government should do. It is still possible to do this and keep control as local as possible. The state can simply allow cities to get x% of county tax dollars in areas where the city is providing services to none residence. You can even go so far as to make it a direct fee that is added to their property tax but that fee needs to be set by the state and not by the city. No taxation without representation and all of that.