I would never attempt to ring up a $500 cart of groceries for feeding a family on my own. And I do buy those. Also, I generally prefer the cashier experience.

However, I do occasionally need to get just an item or two. If I'm at a store that has a self-checkout, it seems to be faster for that.

Also, the checkout at ALDI is an impressive demonstration of efficiency. CostCo seems to have a similar philosophy.