This is a fantastic write-up. Would like to add that some South Asians also do not have last names (that would totally break US systems--wonder what those guys do if they take up American citizenship, like get a last name? Form-generated letters, Dear Mr. <<null>>:)
And Indonesian I once knew said that she had that problem in many places and usually split up her name, which was convenient because the first half happened to be "Susan".
God, I know. Try explaining this to SagePay, whose API requires you provide a firstname and surname. This also falls down if the account belongs to a business. Businesses also do not have first names and surnames.
The only rules I've ever entered regarding real names... is at least two characters, though I tend not to allow numbers, but /([a-z][a-z' -]{,48}[a-z])/i generally speaking... even then, I had to bump that up from 25 characters once.
Not just accents or diacritics, but different characters. E.g. Æ, Ø, Å in Scandinavia.
And we of course don't use just latin character sets in Europe (Greek and Cyrillic scripts are both even official scripts of the European Union), even excluding immigrants.
