Hi and welcome to WAB,
I think it is because of their involvement with people like gardeners who throw them bugs and worms and the young birds learn by watching the parents , they learn to trust humans and accept them ,
I have a couple of Blackbirds that trust me , they come to my feet when I'm sitting and I give them their treat of sultannas, but make no mistake, they are still wild birds and should be respected as such , enjoy their company and treasure the experience,
All the best,
Duncan
