Is it necessary for foreigners to book a return flight before entering Thailand?

Entering Thailand as a foreigner may or may not require proof of onward travel, depending on the type of visa held. Typically, long-term visa holders do not need to show onward travel, while short-term visa holders might be asked by their airline to provide proof, which does not necessarily have to be a return flight. Options such as a bus ticket to a neighboring country may suffice. Additionally, several travelers suggest using services that reserve flights for a fee without actual travel, which can serve as proof if needed.