Irrelevant Gesture

I was wondering if when drivers raise their hand in gesture of thanks to another driver letting them pass, waiting patiently pr whatever - does the other driver even see?

I mean I can hardly make out a constant face let alone a hand waving for a moment.

So who are gestures for, the person making it, knowing they are doing the right thing.

Or are gestures meant to be received? In that case, this hand waving gesture should be phased out.

However, going back to the previous statement...I very often find gestures are only there to soothe the person doing its conscience.