alt Hacker News> I'm assuming it's to prevent moisture from corroding a port of some kind.
The primary value discussed in the talk was electrical isolation since there's mains voltage in the appliance and the potential for shorts or inadequate isolation would require some kind of isolation, so a path that optically isolates the communication makes quite a bit of sense.
I'm also curious if other devices have gone this route.
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Electric meters often blink a signal LED for every X kWh, so other devices can read the signal. I'm not sure if this is used for bidirectional communications, though.
Alternatively, I guess you could also use really thin cables to carry the low voltage paths; and that act as fuses, if ever a lot of current at high voltage was flowing across them? But probably not very reliable both in regular operation and as fuses.
We have a Miele washing machine and a Miele dryer. Solid machines all around even after years of use.
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LG appliances at least used to use acoustic signaling for diagnostics: hold a phone up and the washer makes some modem-esque (I think it’s 4-tone / 4-FSK) noises and the app or technician can diagnose issues. It was originally engineered to even work over voice codecs, so a customer without a smartphone could relay the diagnostic session to a technician.