> Why do rural people deserve subsidies by virtue of living in the sticks?

For the same reason urban people deserve subsidies, for things like public transportation, by virtue of living in the city. The first sentence of the US Constitution lists "promote the general Welfare" as one of the foundational reasons for the creation of the Constitution. There is no "one size fits all" for a nation this size - the welfare of people in the city and the welfare of people in the sticks requires differing allocations of tax money. Also, mail delivery to the sticks benefits people in cities given that mail in the sticks is often sent to or from cities.