Here is the back side of the lens or the film side. If you look closely at the corners of the square part you ill see a circle. Those are four of the 6 fiducials that were super accurate measurement points. The scanners and the computer software would local the middle of the fiducial to calculate the precise center of the exposure.
To illustrate the problem any satellite has no matter how fancy the lens, imagine sitting in a football stadium. Now set up the best fanciest camera and lens and take a picture of someone's face from one side of the stadium to the other. Then try it while moving along at 18,000 miles per hour. Now go stand a few feet from them and take another photo with your cell phone. Which photo is going to show more detail. The cell phone of course.