This T handle garage door lock uses a wafer or disc tumbler type cylinder like many other cheap or lower end locks. These are notoriously easy to rake open. I have seen someone use pumpkin carving knives to jiggle open a similar lock. So if you find yourself locked out, don't panic and start breaking things. Look around your junk drawer for anything similar to what I used and give a try. You can do it.
This is also why you should use a secondary lock on your garage door.