Don't be discouraged when it adds barely any taming. Because maybe they do take barely any taming points from a bite, but they bite constantly! So it is not as bad as meets the eye. Just have a steady stream of Narcotics and berries and you will be fine!
Bronto are slow just shoot shocks or tranqs and walk backwards. Use large rocks to jam them they struggle to cross non flat terrain. Use EXCEPTIONAL kibble to tame high levels or you will be waiting 5-10 min even from starve using berries or veg.
Bronto can carry as many people as you like with or without platform saddle aslong as weight limit is not exceeded. (There is no seat for passangers to mount)