"Euthanasia" just means "good death". And in common usage it means killing something not as punishment or to serve your own interests in some way but for the "greater good"; so executions aren't euthanasia, slaughtering animals to process their bodies or as by-kill in pursuit of some other aim is not euthanasia, and killing for sport or amusement is not euthanasia. Basically, it's killing with regret and respect for the being killed and without selfish intent.

So "euthanasia" doesn't mean what you suggest it means.