Maybe you do not care, but this stuff is extremely important. Airplanes could crash over a few seconds difference!
Electric grids also make use of DC interconnects that obliviate the need for that synchronization. The contiguous 48 US states have at least 3 separate grids that are interconnected. Roughly east/west/Texas. There may be more, but I'm out of touch with it.
Though I wasn't really thinking about phase sync when I was talking about time and cross-border electricity (indeed, hadn't occurred to me!)
Just scheduling, switching, co-ordination etc. It is likely to me that other international things, both physical and logical) rely at least as much on time being accurate to the second.
ITYM 50Hz