You mean America. Not "the West". There is no way that a teacher in an international School in Thailand even earns half the money of a German or Swedish or Norwegian teacher. But the rest of your comment is right: the cost of living. And here in Thailand they often get extra allowences for housing or travel etc.
So, people say you are from Vietnam? That is an ASEAN country. So, rules are different than for other foreigners (like me). Find a law group for business, or dare to ask a Lawyer. Usually the first consulting is free.
As a Vietnamese, it should be no problem. Perhaps a bit costly (no idea).
Registered capital. Not paid in capital into the company. A typical facebook troll. Does not know what the difference is between a registered company with maximum 2 million THB liability versus paying in the money. For a normal limited company up to 5million THB you have not to pay anything into the company during founding.
Then the author of the article was wrong. Phuket is full with western Dive Masters. I now several in person. And I doubt they have a "tour guide" work permit. You could have linked the wikipedia article btw, so that I can correct it.
That is not a tour guide. A tour guide is one who goes to a temple and explains you the history. A dive master teaches you how to dive. What is next? I if I teach you how to sail: I am tour guide? Lolz.
You wont get a job as a simple coffee server. That is in theory a reserved job for Thai. And in practice reserved for people from ASEAN countries. With luck you could form your own limited company and get a work permit if you are "some how special".
With luck I mean: if your business idea is just a star bucks copy: no chance.