Riding a horse requires a lot of effort on your body because you connect with it like in avatar. Why would it be worth it?
Source: I can’t remember and couldn’t find it again, so probably from a post on Reddit that was taken down eventually.

            Walking up to my horse in the big steel room of the stables, I couldn’t help but hesitate. I hated my duty, but I was the only one that could do it. No other runner could ride a horse the whole distance of the camps in one ride. Patting the horse, it nuzzled up to me, his eyes slightly desperate with the need to connect. Taking a deep breath, I attached my link, a long cord that attached to a small port behind my ear, to the port on the back of the horse’s head.
            We ride now? Shallow asked me, nudging me with his nose.
            Shallow was my horse. He and I were water runners. We made sure fresh water passed through the pipe system to the survivor camps. We had to open seven gates for seventy seconds once a week, otherwise the water would be stopped at those gates. But that was just one of our duties. We carried messages, packages, supplies, and especially dehydrated food since it could be rehydrated with a miniscule amount of water. If we didn’t do what we did, people would die.
            But it was killing me. To link with Shallow, my brain required thousands of calories every ride. I had to eat a weird green goop for an hour straight previous to a ride, the goop giving me the calories I needed. They wouldn’t let me sleep after I ate either, even though I swear that goop has some kind of sleeping drug in it. Not that it mattered though, no one was allowed to sleep after eating. We needed to use the calories to rebuild the world. But me especially, I needed those calories to make it through all the camps. If I left a minute to early or ate just a couple mouthfuls less than I was supposed to, the link would start to consume my brain. I’d already lost some of my long term memories during emergency situations when I had to keep riding for hours.
            I once did a double loop of the camps in sixteen hours, and that had nearly taken my sight. Climbing up onto Shallow, I sighed.
            “Yes Shallow, we ride now,” I said, patting the horse on the side of the neck, “Let’s get going.”