The answer will be that your device shows you at a glance whether your uncle likely wants a call. It does this mostly through automatic indicators… • whether

The answer will be that your device shows you at a glance whether your uncle likely wants a call. It does this mostly through automatic indicators… • whether uncle has his device in 'do-not-disturb' mode • how many hours it's been since uncle has woken or arrived-at-work or seen the local sunrise • whether he's in a loud or quiet place, stationary or moving • a live video feed of his public-facing workspace, or perhaps the view from his window But it might also have indicators from subtle learned cues: the device senses if he's in a meeting, or currently in a spirited f2f conversation with others, or in the time/place when he usually engages in phone calls. So if it thinks "now is not good", it can also predict and show the likely next workable time. In fact, you might even just press a button (or vocalize a command) telling your device, "let me know when it's a good time to chat with uncle". It'll negotiate a time with uncle's device, only bothering uncle for decisions if/when it's locally appropriate. Then it will offer to connect the call only when it's almost certain to be welcomed by both ends. All these technologies are likely to arrive, even without a single global time. But once they arrive it'll be easy for more people to prefer UTC. And it'll seem silly that anyone ever needed to write 2,200 words about how hard single-timezone coordination would be, because for people living with such assistive technology, that coordination will be effortless. Sun-locked time-zones were a useful transitional coordination technology, but cheap computing and telecommunication will offer much better options.