[throwawaymath]

Apple actually does. Like I said, that icon is in the article, right after the paragraph I quoted. Look at the images the author included.

The author is making the point that this shouldn't take much effort because Apple already uses different icons.

[CrazyStat]

Which one of those is supposed to be an SSD icon? Top row we have, from left to right, generic external drive, an optical disk drive, time machine, icloud, shared (network) drive, CD. Bottom row we have three types of floppy disks, a Sony MemoryStick, a CompactFlash, and and SD card.

There's no SSD icon.