I provide a counter-example. In the city I live in, there is only one regional grocery chain, and they always have a bagger push your cart to your car for you. Was sort of annoying when I moved here 15 years ago. The parking lot has no corrals for carts, because the bagger always takes the empty cart back.

These carts have, for the last couple years (I don't remember when, exactly), the locks on the front left wheel. It can't be to "disable the carts if someone tries to take them out of the parking lot". That isn't an issue. Though I have not seen it in action, I suspect that if I tried to take a cart through the exit without somehow moving it past whatever device deactivates the lock would have the cart lock up and start skidding (though with the lock being on the front, anyone should be able to just pop a wheely with their body weight and keep on trucking).

That said, I don't claim that these are effective at loss-prevention, but sometimes those jackasses get crazy ideas in their heads and won't be dissuaded by common sense and reality and all those other naive things.