The reason you don't think it's even close to a two way street is precisely due to the fact that the necessities of rural living are subsidized.
If they weren't, cost of living would skyrocket... and suddenly, all natural resources would be unaffordable to most people in urban areas.
This fundamentally doesn't make any sense. Say current subsidies to rural areas are $X. Those are clearly enough to get people to live there, work in agriculture, mining, etc. If the subsidies went away, then prices for some goods would rise, but they wouldn't rise by, in aggregate, any more than $X, by definition.
As you state, current subsidies of $X are clearly enough to get people to live there and do work. If the subsidies went away, then Y% of the workers (guessing close to 100%, but that's just a guess) would also go away, resulting in the prices for some goods to approach infinity -- those goods being tied to energy production, food production, and the like.
This would eventually balance by wages for some of the jobs increasing such that some of Y would return to work, increasing costs of products Z, which would then go back to the urban areas at adjusted market value A.
The end result would be that instead of things like milk and electricity being at prices low income wage earners in the city can afford, it would be set at higher values.
The result of that is that the minimum wage floor would need to be increased so that the urban support workers could afford to make a living. This means that urban products and services would increase in price.
Basically, keeping rural costs low subsidizes the few so that each person up the line who takes a cut of the profits is taking a cut of a smaller pie, keeping cost of living lower. Increase the costs of the initial resources, and you create relative scarcity and create accumulation of wealth at the top of the monetary chain.
How does this not fundamentally make sense? It even follows the laws of physics -- we don't live in a world with no friction, and if you increase the coefficient at the start, the point at which things come to a standstill via waste energy happens much sooner.