You have zero capacity to burn anything down, let's clear that up first.
The utter banality of your one-track album -- seller greed -- is that profit maximization has been a constant since the first Sumerian demanded the most bushels of wheat from his 1 leg of lamb. One party in a transaction can't be the first order driver of price change, because one party can't settle the price, and their self-interest does not change over time.
What does change over time are binary events, like a central bank establishing benchmark rates; a gigantic fucking party (=the gov) using their discretion to distribute massive quantities of money; exogenous shocks like droughts or floods; all of which send large impulses through the system that disturb pricing along its wake.
These things are all far more significant, and more obviously plausible.... than someone arbitrarily charged more today, because they had forgotten to do it yesterday.
Or you know, stick with your framework that the Egg guys stopped being able to "get away with it", whereas the Butter guys are still flying under the radar.