Visible crew/equipment: As the Oracle stands up from the bench, right at the end (after she says "Someday"), you can see a strip of yellow tape on the back of the bench marking the right place for her to sit. (01:54:40)
Visible crew/equipment: In the scene where The Oracle is talking to Trinity and Morpheus, you can see the stage lights in the glasses worn by Morpheus. (00:06:40)
Visible crew/equipment: When Smith and Neo are fighting in the building Smith is knocked to the floor. When he gets up you can see the stage light in his glasses. (01:44:35)
Visible crew/equipment: In the Merovingian's club, when Morpheus knocks the girl back and shoots with her gun you can see the white lights/screens in his glasses. (00:16:10)
Visible crew/equipment: When Neo wakes up in the train station, Sati's dad tells her to, "Leave the poor man in peace." When she runs off, a piece of tape is visible at her feet, showing her where to stand. This is visible in many wide shots, but particularly in this shot.
Answer: They never wanted to have the possibility of it getting set off accidentally, as it would render the entire dock area (and possible more) inert instantly. In fact, they probably weren't terribly prepared for the Sentinels ever to find/reach their location. In 100 years, they hadn't yet.
Rooster of Doom