Those excavators were used to get down to the archaeology, usually a thin layer at a time. Usually through soil that's been plowed for a thousand years. With an operator who was usually a trained archaeologist, with other archaeologists always right in front watching for anything uncovered. It might be a wall foundation, or it might be a discoloration in the soil indicating an ancient post hole or a grave below.
After that it was trowels and brushes.
And many times over, they make it clear that everything was fully recorded before being lifted out of a trench. The locations of the trenches themselves are documented for those who come later. Anything left behind is documented. The context is documented. It's not about trinkets; it's about information.
Watch a few shows; their discoveries speak for themselves.