Im really glad you have studied this topic and thought about it (more than I first thought you were - sorry about that

). One reason why I'm really guick to comment on these kind of things is because Im working in a petshop, and as far as this topic goes, unfortunately I have heard too often guestions like "Can I put a macaw in the same cage with a budgie?". And even your guestions wasn't this bad, I have used to people who just doesn't know, and doesn't want to study either. But im glad you are

And so they know right and wrong. Animal kingdome are amazing and they learn quickly how's the boss.
Better than we people
Actually parrots, as small as budgie or as large as a macaw, does
not have any willingness to understand the word or the meaning of "boss". That is mainly because of the lack of pack hierarchy among birds in the wild.

So you see, they don't have any
natural instinct as far as "listen and do what the boss tells you", like in wolfpacks and among our canine friends (dogs). And doing so will just cause problems, which happen when bird does not start to see you as a boss like you would want (because it isn't supposed to do it in the wild neither is it supposed to do it in our homes), and the bird will only start seeing people as a source of bad things, penalties and forcing it to do things it doesnt want, like stepping up to your hand.

Sooner or later the bird will grow and will start avoiding bad things happening to it, example it will fly away or bite you very hard when you try to make it step on your hand again, or even attack. These problems are very common with larger parrots, smaller ones like cockatiels will usually eventually just use escaping as a way to avoid things.
Caging is another common problem with the people who will force the bird into it's cage; when you're taking the bird to the cage, it will fly alway. Soon it doesn't even want to come on your hand even it was ok with it 10 minutes ago. Now it knows where it's about to end. It has started to see you as a threat, and it will hate the cage even more the next time. Trust me on this, I have gone through it. And I have damaged my other bird's trust so badly, still after years of building the trust it does not trust me, and doesn't even want to step on my hand anymore. And propably it never will. I do not want you to have the same faith.
Many people think that just because parrots are so smart, they are like dogs. That is completely rubbish. Just because an animal is smart and guick to learn things, does not mean it is a dog or that evolution has orginally developed it from the wolves. Bird is so far from dogs, you wouldnt even imagine!

Your first thought must be: "Come on, that is just wrong". But people who haven't "studied" as much about the parrot behavior and problem solving, does not know it and that can't be even expected from them, but parrots are nothing like dogs and should never be treated like one.
My trusty opinion, and very strict one too is that if you want to offer your pet the best life you can possible give, you must understand the pet's natural behavior and use that in the process of training. And petbirds' natural behavior does not include understanding the hierarchy system where one individual is the alpha (boss). But they will understand when human is the source of bad things, and eventually the bird will learn ways to avoid it. Unfortunately, here in forum as we speak, are people who has first-hand experience about higly aggressive parrots, which is caused
only because these people have forced their petbirds to their limits, and the bird has realized the only way it will stop the bad things is to attack the source of it. In the dog world this would've never happend but once again; parrots are not dogs.
So if the forcing is not the way to do it, what is; well, positive reinforcement, where you are on your bird's side, respecting it's natural behavior-system, and make it do things you want. I only use positive reinforcement here with my birds, because I dont want to work against them - I want to work
with them.
I had a problem with my newest add to the flock, 2 year-old cockatiel Veeti. He had few problems; first of all he had been forced to the harness, go in the cage, punished when he did something wrong and he was always all over me. This bird was a wreck! He yelled alot, the minute I took harness from the closet he started flying around in panic, and he wouldn't go inside his cage. The answer was not continuing the way he had been handeled in the previous home, but to start working
with him. He had been here a year now, and he will go in the cage HIMSELF every night when I want him to, we are still training with the harness but he lets me touch him with the harness, he will touch it himself, take the treat putting his head through the "collar", and he will not fly to me if I don't tell him to.

All this is because he trusts me completely, and he knows I am never the source of bad things. So he only sees me as a huge treat-machine that will always do nice things, give him treats, strokes, or talk to him in a very gentle voice. He is always free to tell me when he doesn't like the situation but I am willing to train him with these things. I will treat him when he does right things, so that when he measures the ways he gets more good for himself, he will do things that he will get treats, prays or my attention. And these things do not include yelling my ears off

You can read more about positive reinforcement in Barbara Heidenreich's site
Good Bird Inc. Barbara is the world-famous trainer who's speciality is parrots. Kaijuli also has some articles but sadly they're mostly in finnish.
Advice you can (clearly

) always get when you want here in the forums, and excuse my long message (took me forever to type, I will keep these as short as I can next time)!
