Comment by dsclough
Every time I’ve encountered this in Texas it is at the perimeter of the stores parking lot such that if you park in some of the furthest parking spaces your cart will be locked up when you try to return it to the corral.
I’ve always assumed it is to prevent literally stealing the carts themselves moreso than shoplifters trying to shoplift entire cartloads of stuff.
I confess to being in Texas. But in this city, the bagger always pushes the cart, and returns it to the store. They don't even have cart corrals in the parking lot because this is how they expect it to work. Maybe for other stores it is some sort of cart management solution, but where I am I can imagine no other possible purpose than (ineffective) loss prevention.