When two cars arrive at an intersection at the same moment, even though the right-of-way may be clear under the law, it is a kindness for the two drivers to make sufficient eye contact to make sure there is mutual agreement before one person proceeds.
However, when two cars arrive at an intersection at different times, it drives me crazy when the second driver waves to the first in that falsely-generous way that says, “you go first.” Of course the person who was first is going to go first.
It drives me crazy when people go through the motions of ‘giving’ someone else right-of-way when it’s not theirs to give.
As an aside, the defensive driving instructor has always said in his tri-annual lecture that even if you have the other driver on tape waving you ahead, if you proceed against right-of-way and they hit you, the accident is considered your fault. So driver beware when you see another driver wave you ahead.