I support keeping country folk connected to the rest of the nation as a public good, not a profit center. What, exactly, is the public good in having the rest

I support keeping country folk connected to the rest of the nation as a public good, not a profit center. What, exactly, is the public good in having the rest of us subsidize mail service to rural people? It's not like they couldn't get mail - they'd just have to pay what it costs. Where I live I pay more for land than people in rural areas do, but I don't expect them to subsidize my house. Why do they expect me to subsidize their mail, their airports, and their roads?