There is more than just a loss of situational awareness(in terms of knowing one’s location relative to a runway). There is a lack of attention focus on outside cues. There was a holdshort line and signs that was not seen despite the fact that they knew that there was a nearby parallel runway to hold short of.
Taxiing should be thought of as being similar to flying. The pilot operating the aircraft focuses on operating the aircraft, which includes looking at outside cues.
I would say this incident can be related to going through a stop sign or red traffic light. Why do those things happen? Not paying attention.
At some experience level, a pilot should be able to recognize when heightened attention is required.
I would not be surprised if the pilots had in their mind that there was a parallel taxiway to be crossed first resulting in reduced vigilance.