For a few hours? Sure, why not. They’re not actually useful labor. The store is doing you a favor. Your average 8 year old peeled away from Minecraft and told to do a task is going to fuck up more than they help. I know, because I was that kid and I fucked up a lot. Sometimes in very expensive ways. My only worry would be that they would leave the job thinking every day will be fresh and new like that day, and that people are gracious and polite.
For a few weeks? Oh hell yes, now we’re talking. Then they’ll see the monotony and how much corporate sucks. Even more, how much customers suck. At that point, the value of learning a skill that keeps you out of the fast food/retail mines will be obvious.