Have been at T3 on a few occasions catching the 21.30 Thai flight I would comment that certainly the Thai & Eva are boarding at similar times but have we never been the takeoff queue with Eva . Bear in mind that most long haul flights to the Far East have at least 30 mins slack in push back times-our last TG flight actually took off 65min late due to late incoming and landed only 10 mins late.
If you check BKK times you will see all 4 airlines have similar take off times and one suspects the actual times will be spread over 45 mins because of ATC/loading/connecting flights/late incoming/missing PAX etc.

ps. Agree move to "other Asian" as no airlines mentioned fit into "Middle East/Africa" when I last checked my map (pre 1935- British Empire Globe, loads of red)