I have lots of monitors, they are not untame, they are not mean, they do not want to bite you. You really have to offend them to make them aggressive. Mine will follow me around beg for food, want to be around me, just for something to do.
The point is, you must allow your monitor health and metabolism before you consider its tame or not. You must allow it to be a monitor first.
Any monitor at half its metabolism is tame. Their tame, because they cannot move right. They can only move slow. A healthy monitor has tremedous speed, they can outrun you without problem. They can react at incredible speed, they can catch birds in flight, or catch a jumping cricket in mid air.
Also, a tame monitor is curious, if they are awake, they have to investigate, so they squirm around if you try to hold them. To sit there to me means somethings wrong with the monitor. As that is not what a healthy monitor does. If you pick one up, they normally lift their head high to see whats going on, they then see something of interest and HAVE to investigate it. Thats what a monitor is. Kinda like a ferret. They cannot seem to keep out of anything.
So one sitting there while you pet its ear is odd. Something wrong with it. Its gone submissive. and monitors are not submissive. The are curious intelligent "ACTIVE" creatures. In addition, they have minds of their own.
So please before you go on being mister tamer person, allow the monitor to be a monitor. The cool part, they are not mean to start with. (disclaimer) a percentage of wild caughts have been tortured beyond belief. They indeed have suitable reason to be mean and hate people.
About taming, I have wild roadrunners and wild lizards that eat out of my hands and crawl up on my lap, they follow me all over. They even just sit with me while I am working on our trucks And they are wild. They have no problem doing that volunterily, but they do not like to be grabbed. Cheers