[robryan]

Interaction with someone working checkout can barely even be thought of as human interaction most of the time, the way they generally say the exact lines the shop has told them to.

It's also usually a faster to do it yourself.

[georgemcbay]

IME it is never really faster to check yourself out, even if you're good at it... at best and assuming you only have a couple of items you'll be just about as fast as non-self-service. And most people are not very good at it (I've sat in line behind 4 people all using the available self-service checkout machines, all 4 seemingly completely stumped by the whole process), so those people will be significantly slower than just using the cashier aisle and they'll slow everyone else down too just by the bottleneck nature of queue/lines.

When self service machines first arrived on the scene it was faster to use them because nobody else did and thus there were no lines for them even when lines for the cashier-aisles were crowded. Now more people are using them (often VERY slowly compared to a real cashier) and now the lines move significantly slower than cashier-manned lines. I no longer use the self-service aisle unless it is empty and all the non-self-service lines are occupied.

YMMV depending upon where you are and how recently self-service has showed up, but here in Southern California where they've been around for years it was a great option that turned into a very bad option once a critical mass of consumers felt comfortable enough to use them.

Also of note, particularly here, is that the usefulness of the self service devices depends a lot on their UI/UX. Around here the Ralph's stores have a system that is very streamlined, and the Vons stores have a system that sucks (you have to switch back and forth between using two different screens like 4 times if paying by debit/credit), so that factors into it as well.

[robryan]

Your right that whether it's faster is going to depend on queuing time. Just counting the time being served or self serving a decent person on checkout will do it faster. Generally here though the time to wait for self checkout is zero or under a minute whereas the line for being checked out can take a lot longer.