"Why have a closet that locks from the outside?"
That's to keep the grandkids confined, when herding works better than duct tape.
Really, though, many of those types of locks have a hole in the middle of the handle on the non-lock side. Just keep a good-sized nail taped to the inside of the closet. Push the nail straight in and turn the handle at the same time. Works fine to get toddlers out of bathrooms, too.
Sue