Uplinker
That's not true. 737 A/T has two servomechanisms, one per each lever. Have a look at
, particularly around 0:45, where you will see that A/T can move each thrust lever separately.
This functionality is required to synchronize the engine RPM, as the same thrust lever angle might not result in exactly the same N1, depending on many factors, particularly with these hydromechanically-controlled engines.