I found an oddball online stocking thing yesterday on Walmart.com. I was wondering if I could get Chevron Supreme from my nearest US Walmart, which I drive by about once a month. I went on the website and searched for Chevron 5w20. Up came 5 quart and 1 quart containers, with the 1 quart containers in stock in the store I go to.
Out of curiosity, I wondered what other products they might have, so I browsed to Automotive - Engine Oil and selected 5w-20. It gave me a wide selection of oils in conventional, blend and synthetic. But there was no Chevron. So I redid my first search, and there it was again.
What I learned from the experience is that online vendors will curate the response to an online query to steer the potential customer to certain products, away from others. In real stores, they put the good stuff in front of you and the not-so-good stuff up high or down low. On line, they just don't tell you it's there. It used to be that store suppliers paid extra for "shelf position". I guess it's happening online now too.