The habit of bison to migrate over vast distances instead of staying in one territory makes them somewhat difficult to manage. Combined with the resources necessary to contain them (they can jump way higher than animal that size has any business jumping) and their gender-segregated, fluid social structure (which makes it harder for humans to dominate them), domesticating bison just isn't worth the effort for people with stone-age technology. Domesticating bison IOTL is not necessarily impossible (the experiment thus far has some promising results) but they cannot be domesticated the way cattle or horses were.
You'd probably need some change in behavior for the bison to get domesticated. At very least, mixed-gender herds with one dominant individual leading the herd would allow humans to control them more easily.