it's a "work around" if you don't have tje 800k in a thai bank, so hardly a scam, in my book a scam = pay some money for something and receive nothing back in return. Here they are getting a visa that otherwise would be out of their reach
Use a visa agent like above you can send all documents via email or pop them in the mail, I live in koh tao, my visa agent is in Bangkok for the last 5 years I have done everything via emails ans postal couriers, never stepped foot In their office