Why don't sales people understand cues?

[the b]

I was in a hurry so I placed my credit card on the counter, right after I put the merchandise on the counter. I was polite and everything and even responded to her question of how my day went, but I did that to indicate to her that I'm ready to pay as soon as she's done scanning the merchandise. She took her time, as usual, and then she told me the amount and I looked at my card. And she looked at me and said the amount again, so I said, I'll pay with Visa, here you go. She then took it and swiped it and then she stared off into space instead of putting the merchandise in the bag while the card was ringing through. Then she took her time to put the stuff into the bag, and spent about a good 20 seconds comparing signatures. The whole transaction lasted about 4 minutes, and it could have been done in 30 seconds max. I got really annoyed and wondered if they do that on purpose?