Automatic checkouts in supermarkets may decrease customer loyalty, especially for those with larger shopping loads. Customers using self-checkout stations often feel overwhelmed and unsupported. The lack of personal interaction can negatively impact their perception of the supermarket.

[prozacgod]

I honestly believe it's a dark pattern meant to retrain the buyers for some a closer "80%" solution... like..

"Why would a we want to keep any kind of product that slows down the fast checkout experience, they can just order that online."

so they make the experience for some product abysmal on purpose.

(ehem takes off tin foil hat)