There are four kinds of touch screen in common use, Surface Acoustic Wave (SAW), Resistive, Capacitive, and Infrared. They all have their pluses and minuses, but in the early days of touch screens poor choices were made due to lack of understanding and budget constraints. For most major touch screen rollouts now they use technology that is pretty darn reliable.
With respect, altho there are now highly reliable touch-screens on the market, I will bet that a county confronted with buying a thousand or so terminals that are going to be used (on average) one day a year are gonna go for the absolute bottom of the line cheapest.