I've seen that happen before. I'd like to see the prat try and remember the exact details of every ticket on a train.
I travel from Partick to Blairhill a lot, and often get checked twice because most people get on/off in the Central Glasgow area. I don't make a big deal of it. It's possible that that's been what's happened here (he's maybe been checked somewhere to the West of the City). I generally keep my ticket on me at all times, either in my hand, lying on the table, or sometimes in my back pocket. I don't see the point in wasting everyone's time keeping it hidden in the wallet and making a rather large scene when the guard comes into the carriage.
I vaguely remember coming home from York once one young lady (who was going from London-Edinburgh) went into a strop when the guard asked to see her ticket because she'd already shown it to someone. That someone had left the train at York. Still, she refused to show it again given that it was such an inconvenience to go into her handbag. However, she found it rather more convenient than paying the price that the guard quoted for the return ticket, and eventually realised that pulling a small ticket out of your purse isn't all that difficult.