Simon Jester wrote:

Why do pedestrians thank drivers with a wave for stopping at zebra crossings?

'At some point you’ll almost certainly have seen someone walking across
a road and then breaking into a little theatrical gallop when a car
approaches. Is this the act of someone running for their lives? No. If
it was, they’d suddenly sprint. It’s the act of someone who’s been
conditioned to believe that motor vehicles and the people within them
must be allowed to proceed with minimal disruption. ....'
http://beyondthekerb.org.uk/2015/10/02/we-do-not-negotiate-with-terrorists/

--
john smith |MA (Hons)|MPhil (Hons)|CAPES (mention très bien)|LLB (Hons)
'It never gets any easier. You just get faster'
(Greg LeMond (1961 - ))