Apparently I have a shopping cart obsession

So today it dawned on me..why aren't their brakes on shopping carts like there are on strollers where you can lock it into place so it doesn't roll away? Actually the problem I am facing is my lovely monkey of a daughter. If I stop the cart in the isle to grab something off of a shelf, Laila takes the opportunity to send Landon off with the cart. In other words she pushes the cart down the aisle, which I swear she is aiming for other shoppers to embarrass the crap out of her mom:) I suppose I could whip her into shape(not literally).. which I try...but we are in the phase of her not listening to a thing I say, regardless of her punishments. Anyway..I was just thinking today it would be nice to be able to lock the wheels.