We have more than 4,100,000 ~~million~~ miles of highway in the United States, but only 48,756 miles of Interstate highway. That doesn't sound like most places are just off of a random exit, and with one glance of the map, one can see vast swathes of land nowhere near an Interstate highway. However, the system does carry about 1/4 of all highway miles in the country, so that's a lot of lightly-traveled non-Interstate pavement. Furthermore, revenues from highway users does not cover the cost of the Interstate system. The Highway Trust Fund has been shrinking, because the $0.184 per gallon tax hasn't changed since 1993, and the fund is projected to be depleted by 2028. The Federal government has shored it up multiple times with transfers from the general fund. Wisconsin has done the same, I know, and likely quite a few other states that I'm not familiar with, as well. In short, the massive subsidy to automobile travel, especially in rural areas, is not practical, because it is not sustainable.

Indeed, the topic was people living in the countryside, and (I hope) not about Soylent Green. As for the farms producing food in the countryside, they need to pay directly for the road infrastructure they use, too. That way, the true cost of transportation gets priced into the product, which lets the market allocate resources more efficiently. Government subsidy distorts the supply and demand curves, it leads to what I believe economists call deadweight loss. For example, with subsidized road transport, the cost to the farmer of locating a farm far from the city is reduced. That lowers demand for land near the city, which makes it more attractive to build housing on big lots on the land instead. That kind of sprawl means more driving, more pollution, more environmental damage. Plus, the local government has to subsidize even more pavement, which is becoming a major issue as the burden of maintenance costs is overwhelming them in many places. (Incidentally, lots of farms and food processors at least in Wisconsin face labor shortages, because the workers can't find affordable housing out in the middle of nowhere.) We might benefit from cheaper food prices, but the cost to society is a lot higher than the benefit, hence the "loss" in deadweight loss.