It’s interesting to look for wider and older examples. Back when physical bookstores were more common, I was surprised to learn that the most visible books were often paid promotions from publishers. This was never disclosed to customers — they were led to believe this was purely an editorial choice by the store managers — but it wasn’t. The same is true for grocery stores — the products in the most prominent places don’t get there for free.
In the marketplace there are always forces of ulterior motives, from product producers looking for a marketing advantage, to the store owner simply wanting to sell more, and more profit rich, products.
I agree that digital commerce makes the scale of what is done without us realizing it much greater, and given the data they have more potent, but the notion of pure serendipity where commerce is concerned is sometimes more romantic than real.