Eh, we decided a while ago that certain things are worth subsidizing if they benefit the country as a whole.
Education, healthcare, transportation, retirement -- these are all things where we could say "People can just pay for these things if they value them", but instead we determined that some subsidies are good for the country as a whole (we often even want more subsidies for some of these).
Likewise, it's important to have a population that's willing to live and work in rural industries that supply big city centers. Subsidies to provide some of the infrastructure that more dense areas have can help the nation accomplish that needed population mix more easily.
Education, healthcare, transportation, retirement -- these are all things where we could say "People can just pay for these things if they value them", but instead we determined that some subsidies are good for the country as a whole (we often even want more subsidies for some of these).
Likewise, it's important to have a population that's willing to live and work in rural industries that supply big city centers. Subsidies to provide some of the infrastructure that more dense areas have can help the nation accomplish that needed population mix more easily.