Apparently, you are way out of date in your monitor research, or haven't worked with them very much, except to import and sell them.
Varanids are the most intelligent genera of lizards, and while you say they come to accept people as not a danger, I imagine you haven't let a "trusting" monitor meet a stranger... I've seen this numerous times and they don't just lump people into one general group. They know who you are, and can tell someone different.
I could write many examples of proven research and results, but let's just say that monitors are SMART and deserve to be treated so.
Chris