A mountain's thin air and rocky soil can make it an inhospitable place to grow crops. But for all the challenges these conditions present farmers with, they can reward them in equal measures, such as with cold temperatures, dry air, and reduced dependence on pesticides. Actually going to market, however, requires hauling one's produce down the mountain—a task not for the faint of heart. In some tea-growing regions of Southeast Asia, the quickest way is via the biggest motor vehicles that can maneuver down mountainous trails: Motorcycles. Recent videos uploaded to social media show farmers traversing the treacherous terraces of...