Tron Lines: Averted for most pieces of technology: they are kind of pointless on their own, and inefficiently power-wasteful. (And if a few status displays and such adopt a similar look when there is a purpose for it… well, what of it?)
They are, however, a fashion (a data glimmer; often something like the image on the right) that comes and goes among digisapiences for their trigraphic representations, and even (usually via an AR shimmer, but sometimes regular old LEDs or nanotattoos) for the physical ‘shells of the machine folk. After all, if there’s nothing else to tell a cybershell from a nonsophont robot or a bioshell from a regular member of their species, you have to show off your nature somehow, right? Substrate pride!