That's not true. At least in Germany you can take pictures of people in public places without consent (with certain restrictions). Publishing these pictures is where the "copyright" on your face part comes into play.
That makes the point of grading a student's result senseless. I don't even mean the 'boycott' but that Froehlich adapts the grades to the highest received. That would mean if everyone is lazy/stupid they'll all be evaluated better than they are. So why have a grading system in the first place if it doesn't enable you to compare results indepently.
(btw I would vote for a grade free teaching system anyways)