Wal-Mart Shopping Carts

Has anyone else noticed this? I went to Wal-Mart the other day, and I saw a sign on my shopping cart saying Wal-Mart has implemented a new security feature on the cart that will cause the wheels to seize up if the shopping cart is taken outside a clearly-marked boundary in the parking lot. I assume this is to keep homeless people from taking their carts.

The odd thing is, I looked at the wheels, and I didn't see anything that looked like it could manually lock the wheel. The wheels look normal. And I didn't see a boundary in the parking lot. I'm thinking this is an empty warning. It makes me want to drag a cart outside this so-called boundary just to see what happens.