To be clear, what the author said is that communicating in any language besides Japanese is prohibited with anyone. So if you share a cell with an inmate who speaks your native language, you're not allowed to speak with them in that language. I think that expected to be allowed to speak with inmates is not a sign of arrogance, and I don't know any other country that has a similar restriction.
Another issue is whether the author is allowed to communicate about her case in her native language. If she's asked to sign forms, make statements, or expected to understand her legal procedure, one would expect that the police would provide a translator to ensure that she's treated fairly. Certainly, that would be the norm in the West.
That's not the issue. At least in the US it is unconstitutional to bar inmates from speaking or communicating in non-English languages.
Likewise the US legal system is required to provide you an interpreter who can speak in a language you are proficient in.
Whether these rights are properly upheld in the US is another question but they are rights you are entitled to.
That's the main issue. These are rights that Americans are accustomed to and it's not always obvious to them when they leave the country that these rights aren't universal among developed countries.
This attitude is so unbelievably prevalent among native English speakers. "Obviously everyone should speak *my* language -- why should I ever have to learn another one?"
Seriously, what is so baffling about expecting an interpreter to be provided? Even if you do "speak" the language, this is not some everyday environment, and evidently not a good-faith one either. If I got into a similar situation in the US or similar, you can be sure as shit I'd ask for one too, even though I do believe I have a reasonable command over the English language in general.
