They also served BKK - LAX non-stop, but it was unprofitable because of the A340-500 and fuel costs, nothing to do with grifters. It was a comfortable service, but pax loads were limited to 80% due to expensive fuel needed for the four-burner.
Not many A340 flying any more, maybe Lufthansa still does, but Thai have been trying to sell their half-a-dozen since forever.