Originally Posted by RTWFF
Interestingly I have used a one-way rewards ticket from Sydney to Bangkok and never got The Question about return flights (October). Equally the only time I have ever been asked about onwards travel recently is when I've had a ticket ex-Bangkok return to the US. The United agents wanted to know that at the time of boarding in Bangkok (my return was several months in the future) that I had another ticket out of Bangkok to cover my return journey into Bangkok. It was quite bizarre
The requirement varies by country. For the USA, if you do not have residency status, it is the carrying airline's responsibility to ensure you have the right permission and documentation that is required for entry into the USA. If they carry you there and you are not permitted entry, the carrying airline not only has to carry you back to the point of origin, but they are slugged with a hefty fine for taking you there in the first place.
Requirement for non-resident entry to the USA includes the appropriate visa or eligibility for the visa waiver program, and proof of intended departure from the USA within the visa (or waiver) validity period.
Entry to Thailand may not have the same restrictions or requirements as for travel to the USA. I have no idea what the Thai government requires for entry, nor if they put the onus for verification onto the airline.