Unless it's changed recently, this exact service is also quite common in India and the Philippines, and I would suspect throughout SE Asia. Five years ago one such street typist in India made [url=https://www.indiatvnews.com/news/india/up-cop-smashes-elderly-man-typewriter-54736.html#:~:text=New%20Delhi%3A%20Images%20of%20a%20Uttar%20Pradesh%20Police,as%20he%20was%20sitting%20in%20the%20parking%20region.]the news[/url] when his machine was destroyed by a police officer.

On another key, your article would make a great ad for Olympia:
'What typewriter do professional typists in Myanmar prefer? Why the Olympia SG3, of course! Durable, reliable, and easy to use, this air-cooled wonder can churn out legal documents all-day-long.'

Not that I could ever make a living from it, but a few times a year I get paid to create a typewritten document (most often it's bad poetry).  

Laurenz van Gaalen wrote:

Is it SG3 or SG 3? Pricelists, leaflets and manuals from Olympia use a space between the class and the number; SG 1, SM 9 etc. I think it's logical to write it the way Olympia did, but apparently a lot of people omit the space. I find it confusing, is there a reason for this?

I most often type SG3 because it's the easiest.

From all the Olympia materials I've seen, I can recall the company using one of three designators. End consumer-related items such as manuals would identify the machine (and all other models) with a space: SG 3. In other Olympia documents such as parts catalogues there's normally a hyphen in there: SG-3. And, in brochures and technical documents there wouldn't be a space or hyphen at all: SG3.

It would appear that not even Olympia could decide on a standard way to write its model names and all of the above forms are acceptable. Why the variants? It could be as simple as what a layout artist, copy writer and technician believed was most correct.

For example: