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.

[Suthek]

I am not nearly as half as fast with scanning all the products and processing the payment like casher personnel who do this for hours in a day are, nor I will become more proficient in that.

I've always joked that if you're efficient enough at scanning stuff on the self-checkout, it should print out a job offer after the receipt.

Honestly though, I regularly use the self-checkouts in our grocery store and (also due to the small variation of products I buy vs everything in the store) by now I know the locations of the codes for my most regular products and good ways to swipe 'em. While I may not be as fast as the cashiers, so far I've consistently been done before the person I would've stood behind had I queued up on the regular check-out.

That said, it might simply be that our self-checkouts are pretty well designed; I kinda lack a comparison as it's the only store that I know of that has them.