There's a long, long, long discussion over at ThaiVisa about those entering Thailand under the 30-day visa free entry method.
A theoretical requirement of this type of entry has always been that the person have an onwards ticket out of Thailand and 10,000B. I say theoretical in that in the past these requirements were never checked.
It seems that has changed.
As of early April, there are reports particularly at the Poipet border crossing between Thailand and Cambodia that the onwards ticket requirement is being enforced.
It's not clear at this stage if a bus or train ticket will suffice and it's also not clear if bonefide tourists rather than serial over-stayers are being targetted.
Will post more details as I find them. If anyone has crossed recently, would appreciate a report.
I crossed from Cambodia to Thailand at Poipet/Aranyaprathet on the fifth of April, and indeed to my surprise there were posters everywhere saying people wanting a visa-free 30-day stamp need to provide "valid proof" of onward travel before the 30 days are up. I seem to remember the poster mentioned "air travel" or "air tickets" specifically, but I could be mistaken.
In any case, I was asked for the proof and showed my air tickets for a few days later. I imagine many have been surprised by this, as the rule never used to be enforced. They seemed to be strict about it too, so showing up without the proof could make one waste some days going back and getting a tourist visa for Thailand. And I wonder what they do if you try to return to Cambodia without a Thai entry stamp, will they let you back in?