I agree a quick death was the design intent, but as applied in modern kosher factories the letter of the law has been stretched to break the spirit. Things like hanging cows upside down so the guy with the killing knife could find their jugulars more quickly is not humane to the animals. And the non-kosher modern standard for cows of a bolt to the head is even faster than bleeding out a jugular. Still humane concerns over miss rates, but at least for cows I don’t think kosher is any better.

(Side note that other required parts of kosher meat like salting to draw out blood and removing the ligament Jacob tore when wrestling with the angel have, as post-death activities, no relationship to humaneness of slaughter.)