Why are we still using time zones ?
 

In the past (> 100 years ago) every town had its own time. Clocks struck mostly 12 when the Sun got its highest point. Leter on, because of railways, timezones were introduced. But currently it is a real mess. Daylight 'savings' time (it does not save a second of daylight, but shifts it by one hour) made it even worse, every region has its own rules.
In aviation the mess is really understandable. Why don't we gradually switch over to UTC ? Like we all switched to metric (except the US). But even US units are not so confusing as so many time zones with DST no DST, half hour zones and other crap.
Yes, switching to UTC means getting used to getting up at about 12:00 in NY and 15:00 in California or at 22:00 in NSW Australia and date break in business days in e.g. the Pacific Rim. That makes the 'international date line' obsolete and also the stupid AM and PM used in some countries. We have 24 hours in a day, not 12. But so what ? Shift workers (yes, including airline employees) already have a date break in a night shift.
Getting used to this to is like switching to the euro two decades ago in the EU, but it might be too much for many ?

What is more feasible is keeping time zones, but exactly 24 full hour zones and no twice yearly switching the clock.

I don't think it will be any less difficult to figure out what time of day a person might be at lunch several time zones away if everyone was on GMT.

Daylight Saving Time keeps the seasonal daylight slower to the times when we expect and want there to be daylight. This because more important as you move farther from the equator.

Why? If the argument that having a local time zone at all is for convenience of local times, then those in the zones displaced by 30 minutes or 15 minutes will argue those are just as or more convenient for them.

Or if you are arguing that the time zones need to be strictly by lines of longitude, that creates the other problem that then they will not follow national and regional boundaries and create unnecessary complications for many people, with neighbors being in different time zones.

In this day of smartphones and computers and all manner of devices that can keep track of local time and daylight saving, etc., having a 100 time zones is probably just as "feasible" as having the ~35 or so today or the "ideal" 24.

Transitioning the entire globe to a single time zone, fewer time zones or even getting rid of DST/Summer Time isn't remotely possible. Airlines and international corporations can and do use UTC for their operations but trying to convince every single nation on the planet to change time zones would quite literally be folly on a global scale.

It's not that we can't all use a single time zone (China does it for a large country), but that we don't need to. With everything adjusted automatically by GPS, it's not burden on anyone to have different time zones across the world.

Yes, all it takes to get everyone on the same time zone is a totalitarian government willing to crush dissent using tanks if required. Easy, peasy. :D

Because there are things where UTC makes sense and things where using local time makes sense. While UTC is great for coordinating multiple events around the globe like military operations where local time may be less relevant, local time matters very much for other things. If we went to UTC globally, things like booking hotels would then vary based on where you are in the world. For example, a check-in time in New York of 4:00 PM eastern time today, 27 December is still 27 December in UTC but a check-in time of 4:00 PM California on Pacific Time is going to be 0:00 on 28 December in UTC once 4:00 PM hits on the West Coast. And as you move further east from UTC, you run into the same issue going the other way on the clock. Also, time-zones help more clearly communicate what hours are standard business hours and other events that like meals that generally fall within semi-similar norms.

Xinjiang has its own time zone (somewhat formally) that is two hours behind Beijing Time (which is actually centered around 600 miles west of Beijing, in terms of latitude), but things like bus and train schedules are fixed on Beijing Time. That system works reasonably well IME/IMO.

UTC as worldwide time is an incredibly stupid idea. People, all 8.2 billion of them, live "locally" not globally. They need a system of time measurement that makes sense in their daily lives, a readily comprehensible framework by which they get up in the morning, go to work, send kids to school, visit the doctor, shop, etc. Most of earth's population has little interest in what happens elsewhere so time zones have no impact on them. Only on a place like Flyertalk would someone think ~8 billion other people should be shifted to a system that makes life a tiny bit easier for a tiny fraction of humanity.

+1
And when people do have to deal with different time zones, they can still translate and understand "local" time and plan accordingly. UTC does not tell me if it's daytime or nighttime in a given area. It does not tell me if it's meal time or business hours or if its sleeping hours there. With local time, If I want to schedule something for what is 10:00 AM in Japan during my travel there, I understand exactly what 10:00 AM is and where that fits in in my day. UTC doesn't tell me that. I worked with several foreign partners in my previous position and UTC told me nothing when trying to schedule meetings with them. Understanding local times in both areas was how we found times that worked for both us and the international partner. Even for regions closer together you can face the same issue. I work with one org in Central time and one in Pacific Time now. Again, UTC tells me nothing about what times might be best for coordinating the meetings and such we need to hold. Local time in each time zone does.

In this case, China is already leading the pack;)

n.b. Xinjiang unofficially has a time zone two hours behind Beijing, but for transportation, it's the same as the rest of the country.

Because it is inconvenient
You go ahead. I and several other billon people will do what is logical and makes sense.

While I whine about getting rid of daylight savings, I still don’t need total darkness at 7:15a so yes I can see that value. This also explains why we all are lucky to globally be an hour spaced as needed.

The intuitive concept of "noon," which by definition is 1200 hours, is that it occurs at or around the midpoint of the daylight hours. Similarly, the intuitive concept of "midnight," as its name tells us, is that it occurs at or around the middle of the night. Any scheme that deviates too much from those long-standing human norms, which go back millennia, doesn't fit people's needs no matter how well it might fit the needs of some machines. As previously posted, 99% of humanity doesn't give a rat's ... about those machines. Telling them that, in order to facilitate some aircraft scheduling algorithm, they'll have to get up at 11 pm (2300 hours) to be at work by 1 am, is a sure recipe for whoever tries to decree it being fired, voted out of office, or shot at dawn.

Even exactly 24 1-hour timezones is still a human construct and creates problems where humans inhabit the planet versus you draw those 1-hour lines. If it was all relatively barren, it would be one thing. However, do you really want to be in a different timezone from your neighbor next door?