I have to admit that I’ve never had a problem with the scanners (other than in shops at London Airports where they need to scan your boarding pass before they put a purchase through – that normally fails).
LuganoPirate, regarding the searching and retrieving, I can imagine that some people who are unprepared, could create further delays by not really knowing what to do or how to do it fast enough – that said, one can be organised and have the relevant (e-)documents ready when they know they’re needed. I agree that unnecessary delays are frustrating!
A small piece of paper saved though over millions of passengers, is one little forest surviving to see another day! 😉