Coz elderly people can't sit like that.... It would displace their hips!

If shit happens, assholes probably too :-)

I have exchanged emails with correspondents in ca. 150 countries over the last 15 years.

Just like you I noticed that some American citizens go straight to the point and find it is a waste of time to start with "Dear X" and end it by "Best regards". I didn't have this problem to such an extent with Russians though.

I got used to it but I never reply to strangers writing to me like this in private whatever their position is. 

Ooo er, times really are a-changing.  Not only do employees tell customers off for being rude, they’d like to give them a piece of their mind as well.

And as for the elderly looking askance at the offer of a seat, well, would you fancy parking your posterior on something that’s been mis-used?

In the days of telexes before the web, I worked for a trading company in London.  Our head office in NY noticed the amount of paper that was wasted by the trhee of four lines required to insert regards Fred R. etc.  This was not time and motion just something noticed.  So we receieved telexes from NY which would be headed PSE/FR for instance (recipient and sender) and much paper was saved.

It could be a hang up from those days. In London we ignored this except when tlexing New York

Maybe you could explain why your original post did not start 'Dear all.....

In my case it is no longer a case of saving paper (just laziness)

It is a matter of education.
Nowadays we found more and more people unkind everywhere.

"I don't care if someone offers me a seat in the tram. I want them to offer me a seat in their board." Käthe Ahlmann, German Businesswoman

But seriously: It sounds as if you want to be treated with respect:

Avec toute ma gratitude, je vous prie d'agréer, Mademoiselle, l'expression de mon profond respect.

You ask "why", but I don't think you tried to find an answer hard enough.

In your eyes, the senders are impolite because they omit salutations because for you it is normal to use them - for you, e-mails actually are electronic letters.

Now pause a moment to put yourself in the senders' position. Why would they be impolite? If you don't work in a complaint department, it is rather unlikely that this is their intention.

Maybe Paul E is right and this "let's not waste words" attitude comes from the old days where words wasted paper.

Or for the senders an e-mail is not a letter, but rather a written conversation. Where you don't start each reply with "hello" or "dear" and end it with a salutation. So it may be a different "communication culture".

I have many clients who for whatever reason seem rude to me as long as I don't try to understand where their behaviour comes from. That's why no matter how busy I am I always take a moment to question my impression.

Even more when dealing with non-native speakers (being non-native myself).

Preciosa. Problems at Naville are minimal. If you want to relax, read Bill Bryson's 'Neither here nor there ' where in chapter 11 he tries to buy a train ticket from Gothenburg to Stockholm, not speaking Swedish. 

An extract which is very polite

He regarded me sadly. 'I'm sorry, I do not speak English,' he said

I was taken aback. 'Everybody in Sweden speaks English,' I protested feebly

His sadness grew. 'I don't'

Very polite but the result is the same

hhhmmm right now am dealing with a case from Sotshi in Russia, and I find them very rude.

I saw the bellow comment of yours:

"these days parents are stupid and lazy! not even important are they from england or france or from moon. Stupid and lazy! It makes me sick to look those 3 years olds who walk, talk and then been treated like little babies! whos fault? Parents!!"

And I was wondering, why cant some people be a bit more polite and less offensive and then I saw this post.......

hahahahah, I am sorry Mona Haidi. But lazy parents do know who they are. And thats it. IF you know you are not, where is the problem? And this baby thing is not about emails

sad is that they are rude. Very rude. But i wish sometimes they just could be nicer. They are not anymore empire they use to be but I guess it just is not fitting in to their hearts and heads.

Thanks Merike but somehow it has been solved thanks to the saudis

What a pile of BS again. Prejudiced comments. I know tons of Russians & Americans who are lovely, polite and caring, you get back what you do yourself.....  I think all the Estonian people are child molesting alcoholics. Just as prejudiced and for sure utter BS

I work daily with colleagues in many countries. Yes correspondence from the US can be very rough and appears rude, Russian correspondence generally depands on the purpose and the person, and you are correct moreso it is getting rougher as the country enters more and more of our common market places. You must also consider intereptation of the written word, it is very easily misinterperted, if you pick up the phone to the 'rude' russian author, 90% of the time you will be shocked to realize he is the nicest person in the world. This is how business is done in these countries, fast and furious. I was once scolded by a senior VP in Washington DC about why my mails were always so floury, 'get to the point already'. Then a few weeks later i was scolded by a VP in Germany for being too blunt, So two sides to the frying pan, why do we have to assume our way is always best? I adapt my writing style as per country. What you are encountering is a lesson and the best thing you can do is adapt and don't take it personally.  

Nicely said Kevin, can't agree more!

scolded by a German for being too blunt... that's funny :-)