First, since they assume Janosik is just like Robin Hood. They take something they know and project it onto something else. Though, I guess that this is an inevitable part of human understanding, however, I still think that the comparison could have been made better, rather than just bluntly in the title.
Second, this raises the interesting topic or romantic notions vs reality. As much as people love folk heroes with noble hearts, the more one looks into the basis of reality for any such legend, the less perfect it becomes.
I see what you are saying, but I have yet to see this trend go the opposite way. My quip is that Anglos and Germanics very frequently completely anchor their understanding of the world from their own POV.
To Anglos, Janosik is "The Slovak Robin Hood"
To Slavs, Robin Hood is an Anglo folk hero akin to Janosik.
Maybe I am splitting hairs, but to me there is a difference there. One is decidely less presumptuous.