First off, lock repair isn’t for everyone. If you own a large apartment building and have over 100 keys given out, chances are it will be far less expensive for you to repair the lock instead of replacing all the keys that are there.
But if you are dealing with a lock that has important value, then it will only make sense to ensure that the lock is repaired instead of being replaced.
This is especially true for people who have high-quality locks or sentimental, ornate locks. Often family-owned homes for many generations will have locks and doors and parts of the home that are much more expensive because they are practically antiques.