Which is possibly one of the (admittedly probably very minor) reasons why they were left so far behind economically. Focusing on form over function in communication can be very counterproductive.
Not that I'm saying that saying "Hello, how are you?" to someone is waste of time. However certain people/cultures really go overboard with this and expected outsider to comply with these norms when they have much better things to do is not the most sensible idea.
I'm not claiming to be an expert on the matter, but I have a lot to say on it. (Shocker! Someone on the internet with an opinion! (: )
I believe you may have hit on the crux of the thing, if by accident. From my own perspective, it seems that the proper greeting is the most important matter - it is more important than the work you have in mind. There is no "better things to do", because the relation and respect of the thing leads to those work things.
Maybe giving an few examples would make some kind of sense.
Example 1:
"I am in a rush I can't follow formalities!"
"I don't deal with people who rush."
Example 2:
Imagine someone who pees on the floor in your house because they exclaim that, "It is too much effort to go to the bathroom, access the toilet, and clean up afterward!" Would you invite that person back into your house after that? Would you have a desire to work with them, and keep a beneficial relationship going with them? Maybe? Depending on who they are, or what the circumstance is, but for most circumstances, sensible people would answer with a very firm, "No. Of course not!" because what they did is gross and rude. What they did is plainly disrespectful - it is a disrespect of laziness and indifference. They do solely what benefits themselves and have no interest in how that may impact you. It is contemptuous.
In my mind, a working relationship, is the result of having a relationship with that person. It is something that advances from having a bond with that person. You offer them respect, they return it, and in doing so you can be assured that they aren't a crazy person, or are going to do something that puts you in a terrible spot. The fruit of that respect, that bond, is a relationship that permits you to work with them.
You are entitled to no adaptation from others. Your reactions to their "errors" are your problem, and your responsibility, although of course you can choose to start a fight over whatever you want.
On the other hand, if you do not adapt to them, sometimes they will choose to start a fight over it, or be offended, or whatever. As such, if you want to improve your social outcomes, consider allocating energy to adapting to others.
See? Simple. No centralized decision-making necessary. Each person can ruin their own life however they choose.
Asking for a hello is holding the information until I'm engaged, at which point we should just meet for 5 minutes because it will be faster.
Say, you're in the same town as a friend and want to meet them. The American approach might be to ask, "Hey, I'm in town. Want to hang out?" The sender has done their job of delivering a clear message.
But some cultures would just say, "Hey, I'm in town."
That removes the pressure from the other person to say no, I don't want to see you.
You can also bat it back and say, "Joe's is a nice place to eat if you like burgers," which hints that you're available to have lunch together, but it could also mean a polite "ok".
But the ack is there to make sure the other person is paying attention before delivering the message, so they don't misinterpret it.
I don't necessarily think one is better. TCP vs UDP. If it's an important message, an American might still say, "We have to talk."
Are you aware that it is polite to start a convo with people from South Asia with a small greeting? They wait for you to ack. If you don't ack, they will not continue.
It is an important part of intercultural communication to continuously adapt to different communication styles.
Why don't people write a tiny chatbot that applies to certain users? When the person says: "Hello." The bot can reply: "Hello!" It seems easy enough.