If I'm going to Laos, especially if it's to apply for a DTV visa, can I just go by bus? To get a visa on entry, they say one needs to have a return ticket already booked, and the same goes for the Thai embassy in Laos when applying for DTV.

My question: can this return ticket simply be a return bus ticket? Or does it necessarily have to be a plane ticket? And if so, please explain why. I need answers from people who have a clear answer from someone who knows, not someone who's just guessing and think they know.

Thanks!