bc predates the usage of Ctrl+C for copy pasting in some graphical UIs (not even all of them) by at least one decade. And it's not the sort of command line tool

bc predates the usage of Ctrl+C for copy pasting in some graphical UIs (not even all of them) by at least one decade. And it's not the sort of command line tool that you'd reasonably expect a clueless novice to stumble upon. And even if they did, bc terminates gracefully and leaves all your inputs on the screen, so there's not much lost if you do accidentally terminate it mid-work. So there's no really good reason for that behaviour… which is probably why not all bc flavours do it. GNU bc as shipped by Arch e.g. does just silently quit on ^C, and far as I can tell they're not patching it either.