@David ******
Chris chop I'm not disputing you have never had a problem, I'm just stating, there have been instances when immigration officers, upon requesting onward travel they didn't accept bus tickets, perhaps it's a concern, that you could get refused entry at a land border, into the neighbouring country, and returned to Thailand, a bus into a neighbouring country, is not direct like a flight, it's separate bookings on one itinerary, I'm not sure why to be honest, just aware it could and has happened.