Nobody at the self checkout is holding me up because they are having a chat with the cashier. No one in the self checkout is holding me up because they want to talk about every item I purchased like it's some rare lost artifact. No one in self checkout is causing me to be "in the slow line" because one line feeds to multiple kiosks. No self checkout ever struck up an unwanted conversation with me, or caused me to roll my eyes in irritation with their inability to figure out how to pay wirh some obscure format, or wait for 10 mins for some stupid price check or price compare with a website or another store or whatever.
I get my shit, and I leave unbothered. I'm not working for the company any more than I am by picking my own food off the shelf. I am, however, unburdening myself of other people. I actively avoid places with no self checkout.