Perceiving is believing! In the eyes of the industry or an ignorant bystander it may be reasonable to check tickets in this way, but to the bloke who has just queued for 5 minutes to have his ticket rejected and then find that the gateline attendant has wandered off, is this good service? Nope! Even if the industry finds something reasonable, it's the customer who matters, if they don't like it then they'll cease to be customers.
Quite right, it irritates me no end that on a staffed station (Loughborough) I have to show my failed ticket (young persons rail card discount) to a yellow box on the wall which will telephone someone miles away when there's 2 people in the ticket office, 2 dispatchers and a gateline attendant (rarely at the gateline).
What is the percentage of customers on a daily basis who queue for 5 minutes and have the ticket rejected? And what percentage of those never use a train again?