It's the courteous thing to do.
You're probably lucky if you don't have to work in a shopping center. I have. And let me say, it was rarely sugar plum faeries and gumdrops in a toy store.
I don't mind working with children, or dealing with them for that matter. Sure, they smell (75% of the time), but I like to think some have some basic hygiene. But every day, sure enough, I would see some little spoiled runt screaming and crying about some toy because mommy was on welfare and couldn't afford to buy junior a fifty dollar Nikko offroad "whateverthehellitis". Sure enough, like a wailing siren, their cries would pierce the air of a calm atmosphere of greetings and checkouts. By breaktime, my head simply exploded. Good thing I found out that glitch that gives me multiple lives. Why don't you see if you can find it?
But I digress. If you can't get your brat to shut up in the check out line, discipline it. I don't necessarily mean hitting the child (though that certainly is a good start), but you know, no one wants to hear your eight year old screeching about those pissant G.I. Joe's. By the way, that franchise is shitty. But not as shitty as Leapfrog. Those bastard V-Smiles just piss me off to no extent. They all sit there "PLAY! PLAY WITH ME!" They're all evil. Someday, I'm going to burn all the V-smiles in the world.
Back on track. Oh... Hmm. Where was I? Oh yes... What we need is for children to shut the hell up. If you kid acts up, do something about it. Don't let them scream and whine and mewl their way into getting a toy. NO! Make them shut up! They'll only whine even more next time you come in. Don't cave in to give them something they don't deserve. Little bastards... My high school consisted about 90% of little bastards who got the toy they wanted in the checkout line as kids.
Man. I'm probably the last person that should be trying to tell people how to raise their kids. I believe a steady dose of shoujo anime will sufficiently disillusion children into a fantasy world of happy endings and secret crushes that work out. I'm not saying that's a good thing, just that it'd be amusing to watch the effects. You know, like a science project. It'd be all like: "The effects of shoujo anime on small children", and I'd make the cardboard display really cool. With construction paper.