Our local Meijer has TV Karts. For $1 you can lock a kid in the cart and shop in peace.... So they claim. The biggest problem is there is no front windshield (presumably so the kids can breathe). My kid thinks it's an escape exit.
Also, the doors lock - well they kind of lock. Unless you jiggle them enough from the inside. This cart happens to sit children right at the eye level of EVERYTHING THEY WANT. I end up with more junk than if I had used a regular cart. They are also not so cool to push around.
I appreciate the idea, but I hate TV Karts.