It is always difficult to figure-out pricing when you are a monopoly. For most public service monopolies, the protocol has been to set rates to cover costs while trying to keep an eye on costs. It works, and it doesn't.
The WSJ presumably computed the "US equivalent" rate by using foreign exchange rates, but these are subject to short- and long-term manipulation & distortion.
The Economist developed (and regularly publishes) their deservedly famous Big Mac Index
http://www.economist.com/content/big-mac-index wherein the local price of a near-universally-identical product is used to compute "true" foreign exchange rates.
Of course, no price comparison can stand alone when the product/service actually varies quite a bit from country-to-country. The Japan street-name-and-number problem is easily googled. Less well-known is that, in 1945, sans motor transport (or, if they had it, the fuel for motor transport) the Deutsche Post was backpacking the mail across the Alps in & out of Austria.
Countering those examples are the countries where postal service is, shall we say, less dedicated.
Cheers,
/s/ ikeyPikey