Comment by hansvm

All the small-scale meat packers (not a representative sample) I've purchased from were sterile before they closed before the day and not very untidy during the process. We've kept a similar attitude ourselves when butchering deer, cows, pigs, moose, .... It's just not that hard to keep things clean.

A single fly getting in isn't the end of the world, but an environment with a lot of flies indicates something horribly wrong (no protection from the outside, or maggots and an environment inside otherwise conducive to the production of flies).

You're right that it gets gnarlier as it scales, but as it scales you can also afford to build rooms designed to be pressure-washed without moving the equipment. It's even cheaper and easier per unit of meat to wash a room that way than to hand-wash the damned thing.

Maybe that's the norm, and maybe the listeria outbreak is for other reasons, but the conditions described are bad regardless of how commonplace they are or how much they contributed to those deaths.