You're asking what many do, even I have thought of it...tranqing them takes too long. Poachers like the thrill of the kill as well, they do not care about the animals or they wouldn't do it. It's a disgusting act. Mix the tranq wrong and don't monitor them right and you kill them anyways.
It's all about the profits. They used to try taking the ivory off of elephants and rhinos to stop the poaching, but they ended up losing their defense against others of their kind and other predators and were killed anyways. Plus, many poachers would still kill them for their feet and ears.
Do you have any idea how much tranquilizer it takes to knock out an elephant? Or how much more that tranquilizer costs than a single bullet? How about how long it takes for the tranq to take effect? Or how hard it is to figure out exactly how much of a dose you need? Or how dangerous it is to attempt to saw off the teeth of a hopefully-fully-tranquilized elephant? Or how difficult it is to do all this while being hunted by armed park rangers out to kill you? Plus, of course, if the poachers gave the tiniest bit of a **** about the elephants' welfare, they wouldn't be poachers, would they?
They're poached for their tusks, made of ivory. Ivory will get you loads of $$ in the animal trade market.
Of course, if they cared about the elephant's well being, they would get nowhere.
Would that make it any less cruel?
But they're killed because bullets are cheaper, safer, and more reliable than tranq darts. The poachers who are harvesting ivory don't really care about the well-being of the elephants.
People are bastards, that's why.
Money.
