You might find this video from CGP Grey spot on:

https://www.youtube.com/watch?v=wOmjnioNulo

It expands on why horses got domesticated but not... zebras. The TL;DW version is that, well, horses form docile herds with a lead horse, whereas zebras are stubborn and all over the place. Catch the lead horse and the herd is basically yours. Rinse and repeat for cattle, sheep, etc. Hence we domesticated horses but not zebras, cows but now buffalos, etc.

Now try to recollect when you saw a docile herd of bears with a lead bear steering it. :-)

(And no, I do not think it's realistic. But hey, it's World Building...)

You might find this video from CGP Grey spot on:

https://www.youtube.com/watch?v=wOmjnioNulo

It expands on why horses got domesticated but not... zebras. The TL;DW version is that, well, horses form docile herds with a lead horse, whereas zebras are stubborn and all over the place. Catch the lead horse and the herd is basically yours. Rinse and repeat for cattle, sheep, etc. Hence we domesticated horses but not zebras, cows but now buffalos, etc.

Now try to recollect when you saw a docile herd of bears with a lead bear steering it. :-) There's more to the video but that alone rules bears out.

(And no, I do not think it's realistic. But hey, it's World Building...)