It’s all part of population replacement... after all, donkeys are cheaper than zebra, and they fill in jobs that zebra don’t want...
Plus donkeS are a bit less dangerous. A man not long ago was asked to take care of a zebra that was causing problems. He got there, got out of car, znd the dang zebra charged him, bit his arm, and tore it off. The man did manage to kill the animal, but it cost him dearly to do so.