Why should one not address a venerable as friend?

Controlling the process lead to every goals

When the course of study are very hard to graduate, or when the work very hard to take the goals, the teacher/manager need the very strict & many enough rules to control the process work follow in the plan to goals.
The 7 goals of buddhism are the hardest job in the world: 1. keeping own advantage, 2. keeping social advantage, 3. keeping public advantage, 4. keeping present advantage, 5. keeping future advantage, 6 going to anupādisesa-nibbāna, 7. keeping the buddha's teaching for the public advantage in the future until 5,000 years old. This 7 goals appeared in many sutta, such as in 10 purposes of monastic legislation.
That is the reason why the buddha, the dhamma's manager, gave 91,805,036,000 rules, just in vinaya-pitaka, for the monks. Also, 63,000 dhamma-khandha in suttanta and abhidhamma, included āvuso/bhante in this question. I still not included their ancient commentary, which is larger than the present commentary.

Guru, teacher, means respect, doing hard

There are upajjhācāra-vatta for the student in VN mahāvagga, mahākhandhaka, which do service the teacher more than āvuso/bhante calling.

Student need intimacy and trust to learn the hardest teaching

I often see in the movie that when some student very respect to some professor, they will use "professor" word to call the professor.
Why? They realize that the professor will love them and give them all of his knowledge.
This is still going nowadays.

Teacher maybe not arahanta

Tipitaka allowed the un-enlightener, who graduated bhikkhuparisūpaṭṭhāpaka-course, to teach the new monk. So, he can hate/angry his student, because he is not anāgāmi-ariya. When the teacher bias like that, just a little impolite word can let him stop the teaching. When the teaching is not taught like that, the buddhism will go to the end.

All reason above connect together in kammṭṭhānagahaṇaniddesa

The path of purification, kammṭṭhānagahaṇaniddesa.

The right culture give the previous right master, the previous right master give the next right master

The explanation from the previous generation to the next generation, will specify the future.
If Einstein didn't describe his complicated formula, who can understand his complicated formula?
Tipitaka and commentary are very hard than Einstein's formula. Because even we understand Einstein's formula, we may not understand the whole concept of tipitaka and commentary, even tipitaka and commentary often said "the buddha taught very clear, very beautiful syntax". But why we still confuse in tipitaka and commentary meaning. Why?
Because we still not trust enough in the previous teacher, such as commentary--the tipitaka-memorizer, to learn from them step by step.
For the example of problem, nowadays, people believe in reading study system, then they try to read tipitaka and commentary by themselves. But tipitaka and commentary began in oral reciting study system. So when the readers try to read by themselves, they will miss many meaning and relativity of words/phrases/sentences/paragraphs/suttas/canons. Because reading study system and reciting study system are very difference in many dimension, such as structure, referencing, definition-doing, etc.
So, when the reader just read, they will miss many core of tipitaka and commentary.
How about the thailand in a book compare to thailand in travelling? Is the travelling give the traveler deeper dimensions, right? That is the difference between just the reading and the reality experience. Reading can give you a summary of tipitaka and commentary, but reciting can give the deeper information, quicker understanding, easier study, and more.
This is the reason why the monks still keep the oral study system follow ordering of buddha in vinaya-pitaka, through 2600 years. It doesn't mean we
just only recite follow the order, but actually we found the truth that reciting study system is the better way to study tipitaka and commentary. For the example, thailand discarded reciting study system about 100 years ago in colony war, today I have to ask the very deep question about pāli canon from burmese master, which the reciting study system still going on, because no one in present thailand can understand my question with my description, even my teacher who already read the whole translated tipitaka and commentary. But the burmese pali tipitaka memorizer who study from his previous teacher, can understand my question without any description.
why? The right culture give the previous right master, the previous right master give the next right master, which thai loose them 100 years ago.

Question:

Here is a quote from MN 26:

One, standing up to greet me, received my robe & bowl. Another spread out a seat. Another set out water for washing my feet. However, they addressed me by name and as 'friend.'
So I said to them,

'Don't address the Tathagata by name and as "friend." The Tathagata, friends, is a worthy one, rightly self-awakened. Lend ear, friends: the Deathless has been attained. I will instruct you. I will teach you the Dhamma.

I can understand why the Tathagata might not be addressed by name; but why not as "friend"?
Perhaps similarly, from the Maha-parinibbana Sutta:

And, Ananda, whereas now the bhikkhus address one another as 'friend (āvuso)', let it not be so when I am gone. The senior bhikkhus, Ananda, may address the junior ones by their name, their family name, or as 'friend'; but the junior bhikkhus should address the senior ones as 'venerable sir (āyasmā)' or 'your reverence (bhante)'.

What's the need for, what's the benefit of, the "reverent" form of address? Or what's the harm, if any, in the "friendly" mode of address?
If you can, I'd appreciate answers:

• From canonical sources (e.g. suttas or commentary)
• From post-canonical sources (e.g. later, or modern, articles or dhamma talks)
• From personal experience
• and/or which apply to lay people (when addressing monks, or teachers or other venerables)

---

Edit:
I think that ruben202's answer is ample evidence that it is so, in the culture and in the suttas and other scriptures.
I'm not sure I understand why, though. For example:

• A venerable is a friend -- or are they not?
• Is the behaviour (or mode of address) mere ritual?
• Is there said to be a benefit, some purpose, some effect: for society, for the individual's state of mind or karma, or even for the venerable?

I imagine one benefit may be orderliness in the classroom: giving the venerable an opportunity to speak; another benefit is that it might be somehow associated with "faith" (i.e. being willing to listen without yet knowing); is another obedience for some good reason?
The whole question seems to me a bit associated with some identity-view and so thicket-of-views.
The only answer I can think of is a reference to the sutta (reference required) where the Buddha said that people need some teacher or leader, and he (having none) would take the Dhamma as his -- but that's speculation, whereas I'm asking for answers based on references or experience.

cr. https://buddhism.stackexchange.com/questions/25218/why-should-one-not-address-a-venerable-as-friend/25220#25220