Originally Posted by
steveholt
I find it *extremely* unlikely that DL managed to sell OP's seats between being denied at the gate and boarding. Let alone the idea that airlines, who have had to jump through hoops for two years now, would rather verify test results and have long delays, tons of needed training for agents, furious passengers, and constantly-moving rules and targets. The airlines were lobbying Washington to remove the US test requirements for months before it actually happened.
Indeed, the most likely reason why the OPs wife was denied boarding is because the agent thought the test didn't meet the criteria. Whether she was correct is a separate issue, but the conspiracy theories don't help here. I also agree with others that the fact that another airline accepted it doesn't mean the agent was wrong. And as to what happened *in* Thailand, that's also irrelevant. I've traveled a fair bit the past two years and most countries did not check arriving passengers to see if they meet the criteria and some only check randomly. They rely on the airlines to do the screening.
If you are sure the test results met the country's requirements as listed in Timatic, that's the relevant part.