Here's the thing. Most drivers make dozens of right turns a day, hundreds a week, thousands if not tens of thousands per year.
Originally Posted by mr_nickos_jr
When right turn after right turn they regularly see potential hazards when they look left, and virtually never see hazards when they look right, it is only natural that they are going to pay more and more attention looking left, and less and less, sometimes bordering on zero attention, looking right. It may not be right. It may not be ideal. But it's normal, natural and understandable. Ride accordingly. It is unreasonable to expect a right-turning to look right before he turns right, and to bet your life and limb that he does. Besides, as has been noted, he may very well may look right and still not see you coming (see simple diagram below for how sight lines are easily blocked due to the relative positioning of a right turning driver and bicyclist coming the wrong way)
-----> <-- BIKE
/ Parked Cars