There are indeed rural places in the world with decent public transit, and rural places get the same benefits of efficient transportation as cities. We just don't want to build non-car centric rural places in North America for whatever reason, in fact we got rid of long distance passenger rail here, which used to serve tons of rural areas and was seen as a standard mode of transportation even in rural places until the rise of cars and highways, so public transit has actually gotten much worse in rural areas and the transportation barrier has genuinely been shown to be a major contributor to the higher rates of poverty in rural areas.

This highlights an ugly truth about climate change:

Unless you're an off-grid person who eats your own produce and generates power on-site, being rural isn't green at all. There's a reason Canada gives rural people a larger carbon-rebate and discounts the carbon taxes off of farm fuels, and still rural people scream bloody murder about carbon taxes.

Fundamentally, if you're rural for funsies and your life involves heavy interactions with the urban world (shopping, working, etc) then you're living an unustainably carbon-intensive life. But since we valorize rural people as the Salt of the Earth (and give them disproportionate representation in electoral bodies) nobody can say that out loud.

At least there used to be a time when rural towns were built around rail infrastructure. Canada was built by trains, so originally small towns were dense, one-main-street affairs abutting a train station. But now it's all about highways. And those are bad for the Earth.

Transit depends on density. That can even be tight pockets of density, like a small town with a dense low-rise street-wall and no driveways and parking-lots. But you can't feasibly run transit down rural roads, or suburban keyholes.