Yes, such postal service "boxes" sure are country (or rather service) specific. The first time I was in the US, I did not even recognize those blue boxes; thought it was a trashcan or some other container.

As for a postbox on a coin, I don't know of any others. Then again I did not know this one either. Usually, when a postal theme is honored on a coin (service anniversary and such), you see carriages and mailmen ...
Christian