Saw that today. Don't know how they calculate it though. BKK seemed to have traffic far worse than anything I've ever experienced in LA.
You don't even need to click the link for the answer to that.
ETA: Now that I actually clicked the link I see what your question is.
They say "The average driver wasted 104 hours sitting in gridlock during the busiest commuting times last year, and lost $2,408 each in squandered fuel and productivity."
Presumably their argument it's worse in LAX on average, even if BKK has worse traffic.