@Greg **********
that entirely agreed. And indeed true that any fully legal rules are more strictly enforced when flights are overbooked.
The story reminds me of a sad case a few years back. A Dutch backpacker was flying to Vietnam with Malaysian Airlines. Dutch require a visa to enter Vietnam, but with a visa you don't require proof of onward travel, a bit similar to Thailand (but with the difference that also at the application stage you don't need proof of onward travel there, whereas Thailand requires that). His docs were checked and approved in Amsterdam at his initial departure. Then suddenly in KL, his docs were checked again, and he was supposedly required to have proof of onward travel. They kicked him out and didn't even give him the opportunity to still book something. He then entered Malaysia.
Ironically, Malaysia requires proof of onward travel. Instead of preventing him from unrightful entry, they made him have one instead. Clearly they weren't interested in preventing unrightful entries, but had an overbooked plane. Complete idiots.