What is the importance of an onward travel ticket when flying to Thailand?

The 'onward travel' requirement for entering Thailand serves as a precautionary measure to ensure that travelers have plans to leave the country before their visa or allowed stay expires. Airlines are responsible for ensuring that passengers can demonstrate proof of onward travel, as failing to do so may lead to the airline having to cover the costs of repatriating travelers denied entry. While some argue that an onward ticket may seem pointless if denied entry, it is crucial since it can prevent complications and financial liabilities for airlines, as well as reduce the likelihood of being denied entry at immigration.