Don't the animal shelters have something in place so they aren't euthanizing the wrong dogs?

This question came to mind because of this. Some guy doing some work got in these people’s back yard, unannounced, and their dog bit him. So the city put the dog in the shelter to observe him for a week…and the shelter accidentally euthanized him after just a couple of days.
A friend posting on the thread said the same thing happened to a friend of her brother’s.

Don’t they have some process in place so this doesn’t happen? Maybe put a big red flag on the cage, or something? Anything?