Painlessly slaughtering cattle isn't trivial. You want to destroy their brains as close to instantly as possible, but their brains are tiny and their skulls are large, so it really requires care to make sure the animal is instantaneously killed.

I would completely support requiring direct expert supervision of every single animal slaughtered. This is the norm at the smaller operations, but something like 80% of US cattle are slaughtered at giant Chinese owned factory stockyards.