You're right, you're not an economist. Property taxes generally go to pay for services and while some might be at the state level often the majority is at the local level. That means the city or town roads, schools, parks, police and fire, etc. They don't give you an option to pay those because by just existing in the city you benefit from them.
1. Police: How can you pay "for use" on police? You benefit by them bringing down crime in the general area, you can't effectively fight crime on a house by house basis.
2. Fire: Again, you can't effectively protect people from fire on a house by house basis unless the houses are out in the boonies. In a city or suburb if one house goes up it can start secondary fires around it so the fire department has to show up to stop a widespread fire. Even if your house isn't the one burning you get a benefit when they put out the fire and keep it from spreading.
3. Roads: Even if you don't drive that stuff that's in the store definitely came there on a road.
4. Schools: People paid for you to go to school if you went to public school, now it's your turn to pay for the next generation to go to school. Also, from a purely selfish standpoint I want kids to go to school because at least then there is a better chance they won't end up as a leach on welfare or even just spending their days being idiot kids and causing trouble.