M44 (Cyanide Device)
en.wikipedia.org
en.wikipedia.org
Similar devices have been used with sodium fluoroacetate ("1080") in Australia, which is even worse in some ways -- sodium fluoroacetate is less immediately lethal, but there is no known antidote.
"The grower groups emphasized the economic losses associated with predators killing livestock and reiterated their position that M-44 devices were an important tool for protection from coyotes."
There's evidence that suggests[1] that efforts to control Coyote populations by killing them off are less effective than we thought - as the Coyote population drops in one area it creates a vacuum filled by coyotes from another area + increased reproduction, resulting in areas that underwent "coyote control" having spent a lot of time/money/effort and being back where they started at the end of it.
I can't verify a word of this, but I found the possibility interesting.
(I'm generally against any indiscriminate traps like these. I'm fine with hunting coyotes, but a device like this is too much of a risk to non-coyotes - as other commenters have already pointed out.)
1. https://www.npr.org/2019/06/14/730056855/killing-coyotes-is-...
Regarding private property, what guarantees that people will remove these when they move? Or remember where they put them? I remember finding old school traps on my parent's land growing up, left there by a previous owner. Most were not loaded or rusted beyond operation, but some still snapped when you hit them with a stick. From the pictures, I'm not sure I'd spot one of these devices while running around in the woods...
For the same reason I'm not allowed to duct-tape a shotgun to a chair and tie the trigger to my doorknob.