It has to do with processing.
If you use a U.S. based merchant bank or processor, there are terms not allowed. This is one of many examples. If you use a EU based bank, it's a different ball game. It's not to say 'every' prohibited word is allowed, but they are not as strict. Keep in mind, this can vary based not only on MC/VISA, but the merchant bank or 3rd party processor. Each one has their own 'guidelines'.
In the end, it comes down to the region and your VISA/MC/merchant bank restrictions.
