My grandmother used blueberry pie filling for her benchmark of "is this store cheaper than that grocery store?"
One store has four brands that range from $2.99 (on sale from $3.29) to $7.99 (on sale from $9.59). Another nearby store has a single brand at $9.49 that's marked as local.
Given this information, which store likely has the less expensive food?
Furthermore, it was her marker for inflation - she knew what blueberry pie filling cost the previous month, the previous year, ... and many previous years to that.
She lived in a small town in the rural south that had a general store - any grocery store was a forty minute to two hour drive away...
It was a consistent thing that she could track and measure across the months and decades and compare when shopping (is this a store that I get only the essentials for the next week or is this a store that I should stock up on and come back to?).
So too is the pelican, or the raccoon with a radio in a where's Waldo style drawing. It's something to measure across models that is consistent.
Fortunately, none of the stores caught onto my grandmother's preference for blueberry pie filling.
One might worry about pelican maxing... or raccoon maxing... and Goodhart's law gets into the question of "do LLM testers use that for testing too?"