Earlier quoted context omitted.
> Suppose I see a squiggle on some program. Where do I go to look up its meaning? I can't even type it in. It's either one of the well known vocabulary of icons used across programs (e.g. floppy disk for save, house for "home", x for delete, etc), or a new one you can just hover over and read what it does in the tooltip. After the first time (or couple of times), you don't need to read that again, and you'll recogniz…
Tooltips aren't always used. A further complication is that people tend to copyright icons, so the icons from one app to the next are substantially different. > x for delete I've seen 'x', 'delete', 'del', and the trash can. 'x' is also used to cancel or close. There's little consistency.
Well, those would be bad interfaces. But the standard in OS X and Windows apps is to have tooltips.
>A further complication is that people tend to copyright icons, so the icons from one app to the next are substantially different.
Is that a thing? They might not be able to show the exact same design, but they'd still be able to show a floppy disk or trash can or whatever.
That said, OSes could (and some do) provide standard sets of icons to be used across apps, and only special app-specific actions should have custom icons.