IMO price fixing is a lot more common than most people assume. The normal textbook economics say that in a pure commodity market like eggs, the average producer should make near zero profit. There are a few ways to make a profit in these industries, such as economies of scale or innovative use of byproducts, but it is very tough.
On the other hand, price fixing is relatively easy, and as long as the players don’t get too greedy and don’t leave a paper trail, they’re unlikely to be caught. The only way it usually happens is if there is a whistleblower.
The ADM lysine case years ago also threw a lot of cold water on whistleblowers when the whistleblower ended up getting more jail time than any of the other conspirators.
Anyhow, the fact you even see any successful prosecutions given how hard it is prove, and the paradoxical fact that in some commodity industries, you actually do see decent profit margins tells me that this sort of thing is actually probably very common.