Libraries' mysterious motion-sensor sinks

Why do the motion-sensor sinks in the restrooms around here work so poorly? [3586C]

[written in answer space:  It’s all part of the water conservation initiative and the idea is that a majority of people will get frustrated enough to resort to antibacterial no-rinse-required spray.]

Interesting theory, Secret Scribbler.  But it’s more likely imprecise technology than the administration’s plot to force us to use antibacterial no-rinse-required spray.  As evidence I present the fact that, while washing my hands recently and standing a good distance from the Cormatic Automated Touchless Towel Dispenser, that device shot out the prescribed quantity of paper towel.  “What the hell,” I exclaimed, at which point the Cormatic responded by dispensing another quantity of paper towel of the exact size.