A mobile phone is the one exception for that rule. The clock sets itself up, and it's something you carry around, sometimes to places that don't have other clocks.
But yes, to the people designing every other product: When people want clocks, they go out and buy one.
My kitchen is even worse, because every appliance there use LED displays. They don't just stay there blinking, they also shine.
I wish I could find a dumb phone with that capability. On my old Nokia (new dumb models as well) the clock is reset each time SIM card is changed (and I think sometimes if the phone runs out of battery).
