in similar markets (telephone, electricity, and even things like postal service), there is a concept called the "universal service obligation", the cost of which is borne by people in the metro areas. Otherwise, service providers would just cherry pick who to serve.

Metro areas subsidize rural areas heavily. And while it's generally a reasonable thing, that subsidy probably results in otherwise uneconomic development decisions sometimes (e.g., if you're building something 5 or 10 mi from the nearest power pole). I don't know where they draw the line in cost sharing for the extreme cases.