You make me want to spy on these little baby eggs! I wonder if they get used to handling when you candle with a gentle hand and they can feel the routine. When they hatch, they feel your hand picking them up similar to the motion of when they were in the egg? Maybe that's where imprinting can really go, if people take it there? They say baby humans have senses before they are born, why not animals before they hatch? Maybe part of the reason that some people (maybe not hatcheries, but they have it down to a science...regular old job's don't have that, but they do have the compassion in their hearts to really show these animals that you are having a physical contact between you an it, give it something to remember from when it felt safe inside the egg.
Am I possibly onto something here? What ever we lack in nature's brooding as an anatomical phenomena, we make up for in love and compassion and nurturing of other things.
Take a look at call ducks. People pay close attention, they realize they probably made mistakes, and realize it's up to them to assist in whatever way you can because you made a promise to that little life when you chose to put it into the incubator. Home hatchets are definitely not top of the line technology, but they are 110% heart and that will get you very far.
Now I recognize that there are some people out there that ain't got no time fa dat, and that's okay, you have chosen different priorities, but that doesn't make you any better or worse than me. Different have different agendas and different goals with all of this, but we are still on the same side here. We all want what's best for the birds, no matter what the agenda.