I'm all for eating animals but at least kill them humanely
That's a contradiction in terms.
Humane- "With regard for the health and well-being of another; compassionate."
Is there a humane way to kill something? No. But there are less cruel ways, is what you really mean. But if you have already decided to kill something, are you going to give two shits about it at all? No. Did the Germans try to kill their victims less cruely? No, they used whatever means could get rid of the most the fastest.
We have quite a fast assembly line for killing animals today. That's the main reason we do it that way instead of the way that film showed. Also, we're concerned for the people doing the killing, not the animals. We want the killing to be as less stressful for the workers as we can make it. We want to treat them humanely. And the last reason, is from pressure from people who don't want animals killed. But if you're willing to kill them, it's impossible to care how for their sake. Unless, you don't actually do the killing, just sit home and reap the spoils. Then your conscience might start getting to you because you were under the assumption that killing could ever be humane.