Time zones were originally invented by railroads in the late 19th century because it was inconvenient
for each town to have its own time pegged to the local movement of the sun. But while
dividing the world up into a couple different times is easier than having hundreds, it's
way harder than just having a single global time. That doesn't mean half the planet would
have to wake up in the middle of the night or sleep in the morning. 7AM might be a normal
time to wake up if you live in London, while a New Yorker would be more likely to rise
at noon and an Angelino at 3PM. By midnight, bartenders are still at work in Paris, but
most of France would be asleep even as Chicago sits down to dinner. But if you wanted to
schedule a call with people in Detroit and Dubai, you could just name a time, with no
ambiguity. You wouldn't need to remember if Detroit's in Central or Eastern time. A 6-hour
flight would land 6 hours after it took off, regardless of whether it went east or west.
It's simple, practical, and it's a logical extension of
why we created the zones in the first place.