jpoc:
I'll expand upon this one as the overtake on a straight road in broad daylight is a good situation to explain the masking effect on motorbikes.
I was doing some Google'ing today and I see that AA here in NZ agrees with you when it comes to visibility of things like motorbikes and cars using headlights in the day.
So do you feel the same way about Daylight Running Lights (so lower powered lamps to signal where a vehicle is on the road)?