Never seen it and I travel regularly with them

@Brandon ***********

this is true in my case on several occasions, the airline will not let you onto the aeroplane if you do not have the required proof of onward or a return ticket within the Visa on entry validity date and that does not include any extra days you get from immigration (ie 30 days )when you are in Thailand.this was my experience and I believe it still is is the case

@Andrew ********

not true