[Fluorescence]

I imagine the signal they measure is AB test / throw crap at a wall type scale i.e. they trial lots of lines of product and scale-up and restock those doing great margin/numbers and drop those that don't. They don't care too much about subjective product picker's design opinions or user reviews - if it sells, it's stocked.

I also expect the demographic they are selling to are impulse buyer notebook neophytes. The lettered purpose on the front triggers those buyers. They buy the product and put it to one side, never to use it. Repeat buyers that care about the notebook design probably turn to specialist brands they multi-buy online.