It could also be that, in some circumstances, autocomplete doesn't like the look of "non" as a word so amends it to "none." Personally, I've got into the habit of eyeballing my text to try to ensure that stupid misspellings haven't been introduced by the machine, but it's easy to miss some.

Talking of young illiterate people, one I see sometimes is when people write "tonne" when they mean "ton."

I've seen things like "A tonne of my friends are going .." or similar..

What you have highlighted is correct. I also usually hyphenate in this scenario, so “non-resident”, but I don’t think it needs the hyphen to render it correct.

Again, to get back to the devices we use, their foibles, and the effect it has on our submitted text - on my iPad, at least (maybe different on other tablets or other iPads) the hyphen is on another keyboard from the letters. So, if feeling lazy, I sometimes dispense with hyphens. I notice they are never supplied by the spellchecker.

Noone seems able to spell these days ;)

On another forum I frequent one of the regulars (and a real PITA) used “noone” so frequently instead of “no one” that the admins created an account with member name “noone” and each time he would say things like “noone uses libraries much these days” then his post would be quoted by “noone” saying something like “You talking to me?”. This went on for years and he never seemed to notice. Eventually he stopped posting on the site.

Well, along similar lines, two posts ago I typed "may be" and the machine turned it into "maybe." In that particular case, either would have worked, so I left it. Other times "maybe" and "may be" are not the same thing! I just tried typing "noone" and the machine wants to correct it to "no one," though.

Exactly what we found. This member obviously thought he knew better than the autocorrect and insisted on using “noone”

Go figure!!