> Anecdotally most of the time when a ball goes out of bounds both parties have a good sense of last touch and it's often validated by the third parties

In friendly pickup games it's extremely rare to see any confusion about who touched it last.

As competition heats up it's more common (but still rare) and almost exclusively limited to those who are playing most aggressively / competitively.

I'd put money on this phenomenon bring related to the desire to win. We see this in politics, arguments and other sports calls (that don't involve touch, like if a ball touched a line) as well where the desire to win seems to create a conscious or subconscious blind spot that allows us to be extremely confident in things that would benefit us regardless of the information provided to us.

And again I wouldn't be surprised if this phenomenon increases or decreases based on how badly we want to win.