Same here. We probably worked for the same company....
There are a few reasons for using the Halal kill method. The first is saleability.... Once you have a certificate from the Halal Food Authority, the meat can be sold as either Halal, or not. The second is legislative. There are different rules regarding "religious" killing methods which make these methods favourable in some cases. There still has to be vets and animal welfare people present, as in any slaughter house so the animals welfare is the same. The third reason is quality, especially in white meat. If an animal is killed by electrocution, the sudden surge in blood pressure causes small veins to burst. This creates red blotches in the meat which can be unsightly and have an effect of flavour. The last reason is removal of blood. The best pump to remove blood from a carcass is the one nature designed for the task. Cost the producer nothing and is far more efficient that any man made pump.
Lastly, if the line stops with animals stunned, they have their throats cut by hand before they wake up or are electrocuted and discarded.