Hi Paul.
In a nut shell mate, there are too many people these days full of their own self importance to consider anyone else's situation.
When I started caravanning nearly 30 years ago every lorry driver and about 60% of coaches would flash you to give you the thumbs up to pull back to the nearside lane. Today there are plenty of people ready to jesticulate that it's the second time you've done that today.
Reminds me of the Lee Evans sketch. Lee driving down the road has a driver cut him up, so at the next traffic lights Lee jumps out to give the driver a piece of his mind. When he gets to the car window he finds a 6ft 6" rugger player driving. So not wanting to loose face, this is what he said. The way you went round that roundabout not once (hand jesture) but twice (holding 2 fingers up) and the way you threw that *** out the window (clenched hand waving up and down) was bloody marvelous. On returning to his car he said to his wife who hadn't heard the speech, "that taught him a lesson.
Don't worry though paul, I flash drivers to give the ok to pull in. Oh and I flash others to warn of speed traps (illegal but only if your caught) because too often I've seen very close calls when a speeding car jabs the anchors on trying to scrub speed off, not realising there's a motor cycle up their arse.
Now before I get pounced upon by the usual suspects, I do not condone speeding at all, but also I don't approve of the some times sneaky tactics used by speed camera vans and plain police cars where they have been known to edge people into sticking their foot down. One incident I saw was, a chap in a scooby being followed by a skoda octavia RS who flicked his lights at the scooby as if to say "I want to pass" and then "concidentally" a motorcycle cop was round the corner waiting with his hair drier in his hand. The Skoda stopped behind the scooby and a uniformed policeman got out of the rear seat, and he wasn't the chief super being chauffered.