My newest pet peeve is people that leave their empty carts behind them after paying!

Two times recently people have finished removing their stuff and walk away from it, where it sat empty directly in front of me in the way of getting to the area to pay. I did tell one person they forgot their cart (after I pushed it forward to get it out of my way), just because it was so annoying.
The second time, I pushed the empty cart forward to follow them and get it out of my way. I kept looking at them and then at the cashier. I gave her eyes like, "Can you believe them?!", and as the couple walked away she said to them, "You forgot your cart.". They acted sheepish and took it. But geesh! It's so dumb.
I asked the cashier, how do you forget the thing that you just used? She laughed. She said it happens a lot.
The first time it happened, the person had a few items at the grocery store. The second time it was at Target.
Why is it so hard to take the cart where it belongs? Ridiculous.