"Surely if you run with a lit rear light all the time then drivers are going to be looking out only for lit rear lights..."
Your words not Kim's I think!
However joking aside, I think that "I was only looking for Hi-viz" or "I didn't see them because I expected hi-viz" can really be filed alongside the excuse of car drivers who caused crashes by pulling out in front of (motor)bikes and claimed that as it had twin headlamps they had "thought it was a car further away",* what the late J Wayne might have termed "Horsesh*t"!
Or a convenient excuse for an "otherwise law abiding motorist" to hide behind in court after committing an act of criminal stupidity/carelessness.
*Genuine excuse, allegedly resulting in all modern twin headlamp bikes only running one at a time. So if you have two lights on the front of your bicycle look out!