This is a human factors issue and is rare but it does occasionally happen and can happen with an experienced or inexperienced pilot.
I agree. No matter how competent, knowledgeable or well prepared people are, very occasionally they can perform something that is normally routine differently and are unable to explain why afterwards.
It may be something intrinsic to the human condition and the way our cognitive apparatus works. It might be easier to accept that we are all susceptible to the odd “brain fart” and to develop our procedures with this in mind. I guess that is part of the logic behind read backs of instructions, as it helps to trap an incipient error, much as in the “gear up” “flaps up...” “no,
gear up!” example above.
It also shows that doing things in a hurry without time for intellectual examination of your proposed actions can lead to problems. Are we in such a desperate need to get the gear up that we don’t have time to think/check about which control we’re going to use to do it...?