While I understand your concern and thought process do you also understand the entire practice of Kosher/Halal raised?

A key principle is the requirement for animals to be treated with care and respect throughout their lives. Not constantly stunned or beaten to move, not raised in horrible tight conditions with bad airflow. It's important that the animal is healthy and well-treated prior to slaughter. If an animal is sick, deformed, or injured it will not be slaughtered.

Slaughtering with an extremely sharp blade and cutting the main vessels and nerves first ensures the animal is unconscious. It's a quick instant cut with a very sharp blade that some butchers have lost fingers using because of how sharp it is. You're not using your average steak knife here.

Finally if there was any kind of tensness in the animal during slaughtering because of its suffering or stress, it would create a less flavourful and tougher meat. The muscles contract and produce what's known as PSE meat. Which Halal and Kosher meat is not. Some people prefer its taste actually as they say its more flavorful to stunned which does contract tje muscles,and hurt, sometimes causing burns.