Typically something like this is the result of many small things all going wrong.
Basic airmanship is what keeps us up there. Putting as many barriers to the error chain in place keeps things like this from happening. The investigators will probably find a number of factors that caused this to happen.
Things like:
Poor approach briefing (not covering nearby airport if in the notes)
Lack of familiarity with the airport
time pressure, either on time performance or a rush to get there
distractions, flight attendants always call in the middle of this to ask what is going on
failure to follow procedures for on board nav systems
failure to verify with nav systems that runway is correct.
experience in type
lack of proper rest
Answer may include all of these, some of these, or none of these, that is what investigations are for. Any of these or plenty of others could contribute. Usually any one of the failures that is caught can prevent the incident.
That is why you set up an ILS for your landing runway, even if it is VFR. Why you load the runway in the FMGC for an approach even VFR, why we do approach briefings. Nobody out there is above mistaking the wrong runway for the one you are supposed to land on. But it is usually something that is caught a few seconds later when you realize the airport is supposed to be over there, or you are still 15 DME on the localiser etc. Guys in Cubs read the city name on the water tower....
Everything you can do that could prevent a mistake is a barrier to that potential mistake. That is why we follow procedures and verify things.
I will not judge these pilots without a true knowledge of the facts of the situation. My original post was to point out that in the A 320 after a go around the runway is no longer displayed on the ND unless they did clear out the missed approach.