For me, if I ever say IEC mains lead I get a blank expression. C13 even more so.

"Kettle lead" (Which is notched to indicate it can take a higher temperature and most of cables aren't that, they will be the c13 type), and their face lights up and a cable will be handed to me.

Just one of those things that's wrong, but it's not worth being pedantic over it, imo.

Given the paucity of electric kettles in the USA, I wonder how that term became so widespread.

Ironically in Europe where the IEC cables were familiar from kettles, they've largely been superceded by cables hardwired into a base pad onto which the kettle is set.