traveling on cowback

horses. bulls. even dolphins. i just saw a cheese commercial, and a thought passed by my mind... why don't people ride cows? there cute, easy to spot in a sand storm, and most importantly, if you get thirsty on your trip just milk it! sure they're slow,  but  so are donkeys! and if for some reason they don't make it through the journey, you have a bountiful supply of steak, hamburgers, leather, and a cool skull!

why we our farmers so stupid in the past while traveling?