Add to that cultural and climate differencies and it makes it even harder to schedule things. Like there is not a huge difference between France and Spain in term of solar hour, but rhythm is different because people in the south are used to take their lunch break when at the hottest moment of the day and tend to stay outside and up longer because they are most pleasant in the summer.

Most people in europe keep scheduling meetings between 14 and 16 which is pretty much lunch time here in Spain so most of the time I am having lunch during my video calls or take a quick bite in between calls without a proper break.

This might be a “problem” for people who like arbitrary lines to define their lives. Keeping most of Europe on one time zone lets people from different neighbouring and culturally close countries work together without needing to think about time zones.

If keeping most of Europe on one timezone lets people work together without needing to think about time zones, so does unifying the entire earth on a single TAI or UTC "timezone".

No, that does not scale. Sunrise and sunset are at very similar times in CET countries, meaning they have similar business hours, and I can set up a meeting between Spain, Poland, and the UK (which is on UTC/BST, but that’s close enough) at 11:00 CET and everyone will be fine with it and well awake at that time. If we extended CET around the world, and wanted someone in New York to join our meeting, they would be furious because they would need to ~~wake up~~ (edit: be awake and at a computer) at 5:00 ex-EST, or 1.5 hours before sunrise.

Quick, someone tell China this won't work! China has only one official time zone, China Standard Time (CST) which is centered on Beijing, which is on the east side of the country. Some how, the country still hasn't fallen apart since this was established in 1949. Prior to this, China had 5 time zones.

Do you have an example that is not from an oppressive regime that does not care about the happiness of its citizens? Do you have an example that does not have an unofficial time zone [0] observed by people in the easternmost part of the country?

[0] https://en.wikipedia.org/wiki/Xinjiang_Time

I'd say that the biggest problem with time zones is that most people confuse them with time offsets (which unfortunately is what you are doing). A time zone is a geographical area. That area can run on different time offsets - "times". So the UK runs on UTC in winter, and UTC+1 in summer. It's wrong to think of the UK as being in the "UTC time zone".

This may seem pedantic, but the confusion causes real problems with software.

> I'd say that the biggest problem with time zones is that most people confuse them with time offsets (which unfortunately is what you are doing).

The problem is, say, I have a colleague in Spain. I ask him for a meeting today at 0800 CET, which for him means sunrise was at 0746, while I in Munich have had sunrise and got woken up by the cats at 0652.