There are some loopholes in the law and other extenuating circumstances that typically prevent legal action.
I was one of the all-time worst (or best, depending on how you look at it) copycats. Being a homely, skinny, weird-looking thing with two older sisters, it was probably inevitable that I would want to copy them. I both worshiped and despised my sisters -- as anyone with older sisters will understand.
We can all be guilty of this, we see someone who is successful and think that maybe if I do everything that they've done, I can be just like them. It never works that way though.
Friends have the capacity to affect people's tastes, activities, and their lives overall.