I was on the "opening team" years year years ago at target when they started doing order pick up, and my guess is that by giving you 1 string bean, they either:

a) didn't want to go through the questions to ask what you wanted instead, if they were truly out of string beans, so they can tell the machine, "we gave them string beans" despite just giving you one string bean, passing the burden on you.

b) they picked one string bean, to remind themselves to go in the back and get the rest of them, but than handed the order over to the next person and forgot to follow through. (I used to do this whenever someone wanted say, a dozen boxes of cereal. I didnt want to take all those off the floor, so I would get them from the back stock room.

c) they were bored and wanted to have some fun.

d) the system is incredible bulky and hard to navigate, and their hand held said 1 string bean and they dont get paid enough to fight the computer system

e) they're an idiot or in a rush and just saw 1 string bean on the screen and hit clear