Why the hate?

So, it seems that hate crimes against the transgender community may be on the rise in the United Kingdom and I doubt that this is really unique there (don't even get me started on Russia with respect to LGBT hatred). What I don't really understand, I suppose I never will, but why the hate?
What goes through the mind of someone who feels that they need to assault another person simply based on how they're dressed or who they want to be? Is it based on some unvoiced fear? A propagation of hatred taught by others? What drives it?

As a society we like to think we've come a long way on these issues, but I don't know that history really backs us up on that front. Consider the history of trans-folks in pre-European Native society, the two-spirited people who filled valued and very honoured roles in Native society. It wasn't until the arrival of Europeans did this condition become seen as wrong or abnormal in North America and that hasn't really changed ever since. That's not advancement to me.

I don't suppose that I'll get to live in a world that has become free of hate, but one can only hope.