A Professional Locksmith has many years of experience about how the security hardware works, and choosing the proper grade or type of hardware to use in a given situation.
Most of the companies are certified and licensed to practice locksmithing, either by professional associations or by the government where they are in business.
For example, some security hardware, such as a padlock can be very simple as to how it is made or functions, if all you need is a simple padlock, buying it from a "big box" store or hardware store is probably fine. You can go through https://safehouselocksmiths.com.au/ to get the best locksmith services.
What if, however you need a series of padlocks that are keyed alike; masters keyed, keyed to your front door key, need to withstand weather, or are meant to lock up high value items? Consulting with or purchasing your security device from a professional locksmith may save you time, money, provide ease of use, and the proper degree of security?
More important would be the padlocks or security devices on your doors and the windows, are they the proper grade and function? Do they offer the security you expect? Are they properly installed?
Your Professional Locksmith has the answers to these questions, he can offer a selection of the proper hardware, and he has the expertise to install it correctly.