Everyone knows they are non binary

You know what's worse? When the language has a neutral gender, but it's not actually used for most objects, thus effectively just making it more likely to pick the wrong one when you're guessing! And it's full-on clown show when the native speakers don't even agree on the gender.
- I am from a bilingual region where some words are the same but have different genders. And I ended up learning a language where there is a neutral gender but it's made by combining the male and female forms in singular and plural forms, so you can't even tell what gender a word uses just by looking at it, you just have to know.
  Isn't grammatical gender fun? Got even more fun when trendy progressives saw anglophones argue about gender-neutrality for people and decided to apply it to grammatical gender, which really doesn't work nearly as well in languages that use it and ended up being one of many self-inflicted defeats in the culture wars (yes, much more than neutral pronouns in English, because those are actually useful and fit the language well).
- Washing machine could be both male and female in my language. And yes we have neutral.

With all the electronic in modern washing machine how could SHE be non binary?!?

As a rule of thumb any word ending in "E" like 'machinE" is probably female.
To the point that in french poetry, rule is to alternate female and male rhyme. The rule being that the female rhyme end with "E" while any other ending is male.
The "E" rule is not all the time.
So I suppose it is all based on how it "sound". As I'm becoming better in german: even without knowing the genre, I can sometime guess it, based on the fact that it "sound" female or male or neutral. It make sense to rely on sound rather than meaning, since the same word is male in a language and female in others