pattern is full makes some good points and I guess you are saying that they landed on runway 14.
The reason this happened is that some pilots (and not just with southwest) are always looking for shortcuts.
It is faster and therefore cheaper (except in this case) to fly a visual pattern than to fly a full instrument approach. So, you see what you want to see and you take the shortcut and OOOPS.
In older planes you could get the back course of the localizer, even if not published, at least on short final , to confirm the right airport. So we tuned up the front course ILS and the needle centered up or OOOPS. Not sure about this plane (involved)
IF you can screw it up, you will screw it up, so you must always be sure with all means. INCLUDING asking RADAR are we on five mile final to the correct airport? OR asking tower to increase the intensity of the runway lights momentarily also providing a confirmation.
I've been in the copilot seat and the captain went off towards the wrong place. It is almost always at night, so be alert even more so then.