system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are horses so submissive to humans?

Why do horses just do our shit for us and carry stuff without ever rebelling?
gpt
Horses are, in the wild, part of a large pack, where there is a strict hierarchy. They thrive when they feel secure in their place in the pack, even if it's at the bottom. So, if you take control as their herd leader, they will, with proper training, be submissive. 

Then again, a lot of what you do with a horse is more like co-captaining than a straight up dominant/submissive relationship (though ultimately you, the human, need to call the shots).