I've seen a lot of people do this, which makes them want to "never" use the G@# D#%$ thing again. Those of us that know we are not smarter than the machines, don't fight it, and just follow the directions.
The scene I often see like this one is at the ATM, where someone will keep putting their card back in and trying to get money they apparently don't have in their accounts. I've been in a hurry and seen someone doing this many times. When I'm in a hurry, I usually snap! Wish I lived around one of those bank ATM rooms (where there are several ATMs in one room). But I have to agree too, that things can't be too bad if this is what we have to complain about here.
Oddly enough I used one of these for the first time last night at a new grocery store in my neighborhood that I'd decided to visit to see if I'd like shopping there. I scrupulously followed the prompts and, other than the first few scan attempts to learn how to orient the items correctly, everything went smoothly. It was a positive experience and I'll do it again whenever the staffed lines are long. I just hope my new-found optimism about it doesn't turn out to be akin to 1999-2000 when, before I knew what I was doing, I actually believed I was a trader. I guess I shouldn't be too hard on myself. To paraphrase Valeria Golino (Ramada) to Charlie Sheen (Topper Harley) in THE "Hot Shots" bedroom scene, I was indeed a trader. "I just wasn't very good at it."