Santaman is right. First Nations did waste a lot of bison meat. Pretty hard to turn off a stampede.
What you have come to know is that the animal is multipurpose, if and when you care to use all the parts.
Bashing open the skull for brains for tanning hides, crushing big bones for marrow to eat and so on.
Locally, the meat, the head and the hides are used but what happens to the rest (entrails, etc) I don't know.
I can buy hearts for roasting so at least those are saved and frozen.
I guess that I could ask for other parts like kidneys, if I wanted them.
Horses were hunted by paleo peoples.
Seems to me that a horse would have lots of useful parts if you cared to use them.
There's a irregular western social stigma around eating them.
Personally, they taste as bad as llama.