I thought it was just an American thing...I've only heard of it because it has always been referred to in the Trading Post description here at CoolMini.
I think there was a UK version a few years back that just died a death. I guess trading across the pond is a lot easier now though as we are all more used to it.
I've been using it for a few years and have picked up some Rackham figs that were harder to find, and was able to make a trade VS paying out right.
I haven't had any problem but all my trades were US based....