It really "surprises" me how many owners of dogs leave their pet tethered to a post or something similar and go inside a grocery store or restaurant expecting that the dog will still be there when they come out.
I believe there were 2 instances here in OOB where a pet was taken from their yard and I remember an instance where a dog was reported stolen from an owner's truck somewhere in mid-Maine while he was inside a store.
I don't think some owners realize that it's not the dog they have to "worry" about getting loose as much as the possible danger they are leaving their pet in from possible kidnappings or injury from other animals or humans. Especially the small dogs.
I've also known a number of owners who have left their dog in the dog park while they went shopping.
Some owners might feel it would take "too long" for someone to cut their dog's collar off as they're not inside the store for "very long" but many are in a store a lot longer than they might realize.

Now, I'm not saying it's a good idea to leave your dog tied up outside a store...
However I just wanted to point out that if the dog has this leash, they CAN'T just "cut the collar."
The point of the "Dog Lock" leash (I saw the video and info and the product in person as well) is that part of the leash goes around the dog's neck like a collar, and the lock part is what secures the collar part onto the dog's neck.

Basically you loop the end of the leash around a post, and the other end of the leash turns into a collar which is locked onto the dog. There is a steel cable double-looped inside the leash to prevent it from being cut or chewed off...

It is still not a good idea to leave a dog outside a store and go grocery shopping or a restaurant and go eat, as people could harm the dog without stealing it... The leash will prevent theft if you were just running in a store, though.