I have arthritis in my hips. Received positive results at Zen Medical Center in Pratmanuk. Received Stem Cell Treatment and the previously mentioned PRP, and some other treatments. Private clinic so probably not covered under Thai medical coverage.
I don't understand why people are even debating it. It's required by Thailand and many countries, to have an onward ticket. Nothing to debate. If you wish to gamble and not have one, cool. Probably won't be asked. But why risk it, when there are many inexpensive options available. Why would you spend thousands of dollars, travel half way around the World, to risk being denied entry. I don't get it.
Short answer, as in all things in Thailand. It depends. I've been stopped and they didn't ask for IDP. I've been stopped and they did ask for IDP. 95% of the time just waived through. My motto on such things. It's better to have and not need. Than to need and not have.
The kiss of death is to say she has an American boyfriend. Absent that, she needs to be reasonably well off, with a very good job, own a house, own a business... Even then, they will probably be suspicious of a young lady visiting the USA alone.