Even an open source system is a blackbox at run time. It may not be running the same source code/ version as they are telling you it is.

These machines work too fast for people to accurately watch and observe what is going on.

Even if they sever all communications wires to the building, and rooms containing tabulation equipment are placed in a Faraday cage, they'd probably figure out a way around it.

Unless it says all communications wires shall be severed outside the building, and rooms containing tabulation equipment shall be within a Faraday cage. Even then they'd probably figure out a way around it.

Even an open source system is a blackbox at run time. It may not be running the same source code/ version as they are telling you it is.