How do we know that the software developers who created this system didn't put a back door in for their own use? Once the system was in place, they could, for e

How do we know that the software developers who created this system didn't put a back door in for their own use? Once the system was in place, they could, for example, gradually drain the rating for selected members of the ruling elite, or otherwise manipulate the database for their own ends. Trust in software development is critical. I wonder how the Chinese state is guarding against the scenario detailed above?