That is very curious, yes. Eggs seem to just start to increase dramatically after 2000 and indeed outdo the CPI, disregarding the peaks and valleys of the different shocks to egg production like covid and the avian flu.

I read that the price includes free range, eco, etc varieties which are more expensive and in more demand nowadays, probably just that explains a good chunk of the price increase.

I feel like those links are more useful than the target essay.

Reading through them, I wonder why CPIs aren't based on empirical correlational patterns between prices over time? Sort of like in these articles:

https://iopscience.iop.org/article/10.1088/1742-6596/1796/1/... https://www.ecb.europa.eu/pub/pdf/scpwps/ecbwp1011.pdf

Or maybe they are? I'm not an expert in this and reading through some of the government literature there's no mention of this.

Then at least you would know that a given price marker is a good empirical index of how other prices are changing also, at least for a given dimension/component.

Without saying "I bought the exact same brand and type of egg" for 25 years, the data is probably pretty noisy and may reflect the author's income changes as well as the price of eggs.