About a week ago, I found four baby crows which fell down from a broken tree. I raised them until they started to fly on their own. I expected them to come near me when they became adults, but they don't.
Is there any particular reason for this?
Most, if not all, wild animals have a fear of humans. It's very good for survival. We humans have been the apex predator on earth for about 50.000 years or so.
Now birds do have a period of attachment very early on. As in minutes to hours at the most after hatching. In that time period you may attach to you and think you are it's parent. Imprinting it's called. Quite cute how they follow you around when that happens.
But you were too late for that process and their survival instinct is strong. While they probably will recognize you and be more friendly to you then towards other people, you were just too late and their instincts are too strong to become really friendly.