I got told that you are require to show a ticket proving that you are leaving thailand within 45 days if you enter the country on with exempt but do you also have to provide a ticket that proves you are flying out if you have a visa (in my case, a single entry tourist visa)? some folks told me that there's no need while other told me that's mandatory. What is your experience with it? My main concern it about spending money on a ticket which I won't use (because I have to leave the country within 60days while I'd do a visa extension and leave in 90days). Besides of those websites giving you "prenotations" for 15us$, do you have any other solution?
TLDR : Answer Summary
When entering Thailand with a single entry tourist visa, you generally do not need to show proof of onward travel to Thai immigration. However, some airlines may require you to provide a ticket proving you will leave Thailand within your visa duration, particularly if you have a history of frequent entries or if there are concerns about your travel intentions. Many travelers recommend checking with your airline beforehand. If worried about spending money on a ticket you won't use, consider arriving early at the airport to purchase a cheap onward flight if necessary.