I think has a lot to do with manual transmission which allows for natural and controlled engine breaking, thus not creating the brake light to come on (and therefore the wave of copy-cat type braking).
The worst I've seen has been in Johannesburg in South Africa, where automatic transmission is rare. I used to refer to it as concertina traffic before I knew it was called a traffic wave, and the concertina is a popular instrument in South Africa amongst the ancestors of the people who are usually responsible for these waves.