Digital cables are coaxial and have totally different impedance. Apart from the connection, their construction bears no similarity to line level interconnects.
In the same way as a turntable phono interconnect is not similar to a line interconnect.
S/PDIF signals are much higher frequency than the audio frequency range of analogue signals (MHz not just up to 20KHz), and for accurate transmission the cable characteristics are quite critical - much like handling radio or video signals. Much available online that explains in detail. Whilst audio interconnects and S/PDIF cables are both coaxial (though I’ve come across some interconnects that weren’t) so superficially similar, S/PDIF need a 75 ohm characteristic cable impedance, and that includes the plugs.