Because we are not over 1066am.

Not quite chaos but it can certainly be an inconvenience depending on circumstances.

My major client has offices in Eastern Europe, Russia and Southern Africa.

The Eastern European office is usually 7 hours ahead except when it is 6 for those few days when the switch to summer/winter time doesn't align with North America.

Russia has the same time all year and is 8 hours ahead or 7 depending on whether we are standard or daylight saving.

Africa is either 7, 6 or 5 hours ahead because they spring forward when we fall back but the changes aren't on the same date.

Now try and get everyone on a conference call at the same time. At least they don't have an office in Newfoundland where everything is a half hour later.

I don't see the problem with time zones. All my devices and clocks (apart from the wristwatch) adjust automatically.

With one uniform time zone I would always have to look up respective business hours, whereas I roughly know the time in the main time zones.

What can be annoying is the constant time zone changes in the Southwest of the US, where the Navajo Nation observes DST, but the remaining Arizona does not and you end up changing the time even when driving shorter distances.

Not to mention the Hopi reservation. Completely surrounded by the Navajo nation, this enclave observes year-round standard time with the rest of Arizona.

The Hopi nation observes year round Mountain Standard Time (which I think you meant). See, it is confusing!

The single time zone works VERY WELL for China:
-vast majority of population lives near the coast
-center point of the time zone is roughly Xi'an's longitude
-this means that the sun rises very early during the summer in Beijing/Shanghai, but spares the folks out west from 10a winter sunrises
-in Xinjiang, people work according to an informal 2 hour offset (e.g. school starts at 9a instead of 7a), but adhere to Beijing time otherwise

In spite of the fact that the US and China are roughly the same size, I don't think an arrangement like this would be viable in the US simply because both coasts boast large population centers. (China's western border consists of mountains and deserts, and people aren't exactly clamoring to move out there.)

The more interesting question is why Spain is the same as Germany. Apparently Franco did it to curry favour with Hitler and Spain is now considering falling into line with Portugal, the UK and Ireland. Which will leave France an hour different from its neighbours on similar longitudes.

What you are asking actually seems to be the opposite, effectively. Some countries wake at 2am, others at 10am, others at 5pm, others at 9pm. Much more of the world deals in local business than real-time/daily global interactions.

And, fwiw, daylight savings time does not "get longer daylight". Mankind does not affect the stars. Sunup to sundown is the same as it ever was.

While the Prime meridian passes thru France, it passes it slight west of Le Mans and east of Bordeaux. The GMT zone is primarily west of the prime meridian. So is Spain (The prime meridian crosses Spain roughly halfway between Saragossa and Barcelona). France however is largely east of the meridian.

This is first I've heard someone suggest to go to all one time. But I have heard various arguments for the US to go to just two time zones. East and West. And of course many arguments for getting rid of daylight saving time. We are already on daylight saving time for longer than we are on standard time when they changed it a few years ago.

Then there's the whole ordeal of redeye flights. US domestic redeye flights really only go eastbound because the timing works out to leave late and arrive early in the east for morning connection. But going westbound, there are no red eyes, which requires a hotel. Perhaps with only two time zones, there could be red-eyes going both directions?

I love the two timezone idea.^

I've often considered this myself, but IMO the drawbacks outweigh the benefits as detailed above.

I think the biggest issue with time zones is not the zone itself, but the huge variation in DST, with some continents starting/ending before others (Europe vs North America) and worse, the variations within a country. Multiple time zones within a territory and the +00:30 and +00:15 offsets are also making it more complex.

Indeed that is what I told later, this is making a mess of it.

But "the drawbacks outweigh the benefits as detailed above" of a complete timezoneless world is a matter of getting used to it. Like the UK got used to metric in the 1970 or the EU countries got used to the Euro currency.

When the world sticks to 24 full hour timezones without DST then it would already be a lot nicer.

Good to have someone chime in with how they manage it in China. I've always wondered how a single timezone in a continent-sized country would work.

Of course we need time zones. Will one part of the world be in darkness and the other part in daylight? Timezones breaks down the earth into segments.