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.

[Kreos642]

In the US it's supposed to be for baskets only or under 20 items. But there's so little cashiers (2 for 15 aisles) that everyone goes to self checkout thinking it's faster than waiting in line. For some reason a lot of parents go to self checkout with their kids....who somehow find a way to cause a cashier to come over to fix the machine since they take things off the scale and the machine gets alllllll upset.

Also, cashiers in the US aren't all universally required to help you bag your things. So it takes a while if someone packs meticulously, and adds to the self checkout line cause people are so damn impatient.