Might be more complicated than that. If you fine a slaughterhouse, perhaps you are depriving them of the very funds necessary for them to upgrade to stun guns, or whatever equipment a more humane method requires.
Or maybe our commissioner himself is enjoying certain economic advantages by not enforcing the statute.
If it were up to me, I hoist up the workers by one leg for a few hours, then cut the rope and let them fall in their heads into the pig blood/entrails. Then I'd padlock the doors on the place and deny their unemployment compensation.