I mean Booths aren't that small, they're just exclusively north-western & fill the same niche as Waitrose, who have virtually no stores in the north west as a result
That means their customer base is pretty much a perfect intersection of people who won't want to use a self-checkout - older people & people who are friendlier to strangers
Issue is that people like to categorise other people into groups, and so even if you only believe the plausible or even provably true parts of it, if you try and propagate it you'll lose credibility in a lot of people's eyes