That's fair. Price fixing is a specific thing, while I was more referring to facts like:
>BigAg’s consolidated power throttles the price discovery process.
and
> Over time the share of feedlot-to-meatpacker sales done via contract has increased to 72%, so BigAg sets the price outright with no price discovery process at all.
I'm tired and can't even think what to call this except 'undue influence', which is too vague. Though that said, I'd still be shocked if there wasn't price fixing going on, given the state of things.
While I'm here, OP seems to miss that this is 4 players controlling "roughly 85% of the total hog, cattle, and poultry processing market", focusing on chicken where the number is lowest. It's really, really bad; and not something to dismiss based on wild historical speculation.
I think your intuition is very wrong on this one. And since there are clear signs of price fixing which you haven't addressed, it's pretty irrelevant.