We wait in line for the ATM or the checkout or anything else because a scrabble is unfair. Using a tool like this when others almost certainly are not doesn’t really feel fair on those other people.
Having to check manually for a slot sucks, but so does waiting in line, and that’s the lowest common denominator of behavior that still counts as fair which we can all adhere to right now.
I get that the grocery companies should make the slot selection better. But laying the blame on them feels a bit like the FAQ for those padlocks that stop the airline passenger in front of you from being able to recline, where the manufacturer tried to claim we are all in this together their product is just part of a campaign for better airline seating for us all. It was no such thing: it was kind of selfish.
In any other climate I’d happily be told to quit my social justice moralism, but things seem quite serious at the moment, and I wouldn’t encourage using this tool, but maybe I’m taking it too far.