I was typing something up and when I went to type apple in Japanese, the Microsoft IME on the computer I was using defaulted to リンゴ in katakana. But from what I remember seeing online and out in the real world from time to time, りんご is usually written in hiragana as such. What was weirder to me was that when I typed orange in Japanese, it defaults to みかん in hiragana.
The gist of what those three links explain, if I understand them all correctly, is that writing a word in hiragana is usually because its kanji form contains non-standard kanji and is thus for ease of reading, and katakana is used either for emphasis/ease of reading or in academic contexts.
What I was wondering was, unless you are discussing something in an academic context, are words that contain non-joyo kanji almost always written in hiragana?