Planes with wing-mounted engines (e.g., 737) do not use reverse thrust to push back, as foreign objects on the ground may be sucked into the engine. That's why you see S80's doing reverse thrust.

Runways have to be kept clear of debris more so than the aircraft parking area, since all planes use lots of thrust during take-off!

P.S. a ramper/mechanic strike (Eastern?) is when reverse thrust for pushback became popular, and it still is to this day.

[This message has been edited by JS (edited 06-15-2001).]