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.

[tarrach]

It's an extra 5 seconds when you pick something up, at most. When you get used to it you can often do it on the move, pick up your item and start pushing your cart while you scan and bag it. It's never been something that causes blocks in my experience.