I don’t think that’s true - the part about them being virtually indistinguishable. Halal can include bolt stunning which uses significant force to render the animal unconscious

To achieve this in livestock, many Islamic authorities approved different stunning techniques such as a physical blow or passage of an electrical current through the head directly or through an electrified water bath or to induce unconsciousness gradually with a hypoxic or anesthetic gas with different farmed mammals and birds to render them unconscious at the end of the procedure, meaning relatively immediately

These are not always effective and still subject a great many animals to significant pain and suffering.