I bet the first thing that came to your mind, was...
- because humans are evil and hurt animals
- because we're bigger than birds
- because we are louder than birds
- because of all of the above
I am not an owner of a bird. I only admire them. However, I know in myself that I am not an angry, upset, jittery or violent person. I smile at people, strangers and I say hello to people - and yes, sometimes animals like dogs and cats. But when I come across equally as caring and gentle as I can with birds, they fly off. They simply don't trust anything or anyone. Yet when they are in captivity, they just about melt in your hands. Which is why I won't own one as a pet in a cage. I believe that is cruel.
Why should birds, in general, not the prey-like ones because they will attack in the wild, be afraid of people trying simply to be kind to them?
More on the emotions of birds here.