there's a lot of inane comments here.
The simple fact of the matter is that we can't personify reptiles as having a human view of the world. They are however, capable of being conditioned to behave in certain fashions (depending on the individual animal of course) and not be threatened by human contact.
There is even a possibility that some do seek the contact.
However, due tot he fact that we can really only read the body language of a snake and infer the cause of the behaviours based upon a simplistic model (possibly accurate, possibly not).
Warmth and the provision of heat energy for metabolism is a major requirement for any endotherm. If you condition the behaviour of the individual to associate the presence of certain "smells" and shapes with a positive experience, there is a much higher chance of the animal being untroubled by such interaction.
However, as the individual moods of all animals change, we can probably assume that certain driving forces change in similar fashions in the reptile psyche. Again, a snake that is sometimes placid can deliver a nasty feeding response if behaviours are not observed or the survival instinct is just too great at any one time.