People who use cameras (dash cams, action cams, drone cameras), portable game consoles (by which I mean the Switch, yes, but also all those Shezhen "retro consoles"), and a few other things. People do still know what SD cards are, even if they don't have a slot for one on their flagship phone.
Nevertheless, the real issue is more that "saving" isn't really something you do any more; almost all apps now autosave and restore on restart, such that the real action that needs an icon isn't "save"; it's the option you get when you indicate you'd like to close an open, but unnamed project/document without quitting the application: "give this project/document a name."
Nevertheless, the real issue is more that "saving" isn't really something you do any more; almost all apps now autosave and restore on restart, such that the real action that needs an icon isn't "save"; it's the option you get when you indicate you'd like to close an open, but unnamed project/document without quitting the application: "give this project/document a name."