That's one of the issues with golf travel in Asia. I've been to Danang once with Golf Asian and twice to Thailand with Golf Asian. I also did a trip to Chiang Mai and got a local driver who did a day tour around the area and took me to play two different courses.
Golf Asian is reputable and reliable. They arrange lodging and airport pickup. I recently asked if they could arrange tee times in Singapore and they only do packages. I have a hotel there I like and have it booked already. They don't provide tee time only service.
I've played in Hong Kong quite a bit and have used public transportation there for the most part. On Hainan Island about ten years ago, Mission Hills arranged airport pickup and booked four rounds at that complex.
Golf in Japan is logistically difficult and mostly not workable for a solo traveler.
I have rented cars in Australia, New Zealand, Ireland, Scotland, England, and Western Europe. I have not rented a car in Asia.
I liked my time in Vietnam but only went to Danang and had two days of a tour by van with two other golfers in areas around Danang, Hue, and Hoi An. I didn't participate in the all expense paid trip courtesy of my government as a young man, but grew up in the era when Vietnam was on the nightly news.
Charles Lund