A travel writer for the U.K.'s Daily Mail says that self check-in at the airport is for travelers who are "technically savvy, can print (their) boarding card at home and … carrying only hand luggage. Then it must work like a dream. This is, unfortunately, the minority of travelers."
Helen Nicholson recounts her experience at an unnamed airport with an unnamed airline where "passengers unfamiliar with the technology grappled for their glasses, rooted around in their bags for reference numbers and tried to work out how to swipe their passport."
Nicholson concludes, "If there were polite, friendly staff to help it wouldn't be so bad but, as the point of this new technology is to remove the human from the process, there is rarely anyone to ask."