Why don't we have one timezone covering the whole earth?
And instead changing the time work and other things happens depending on where you are. Would be easier to arrange meetings across the globe. Same thing applies to summertime. You may start work earlier if you want, but dont change the clocks!
Because time relates to the position sun and tells us something about what period of the day it is in that timezone. Your proposal would strip off that information, which means that you would have to look up in a different system what the business hours are in another country, when it’s night, etc. That means that you’re basically reinventing timezones by putting them in a separate system, which defeats the purposes and makes it more complicated than it already is.
Sure, time differences might be a bit cumbersome, but timezones have a name and can be converted from one to another. Also, most digital calendars (for meetings, etc) have timezone support and work perfectly fine when involving people from multiple timezones. To find a good moment to meet, you will still have to keep the time difference in mind, but in the current system you can at least take it into account just by looking at the time difference.
you would have to look up in a different system what the business hours are in another country
Don't you need to do this anyways? Different businesses open at different times. Different people work at different times. In some countries restaurants and shops tend to open relatively later and in some they open relatively earlier.
Really it just saves a step. From:
It is 12:00 here.
Is is 9:00 there.
Do they open at 9?
To:
Is is 12:00 here.
Do they open at 12?
Sure, step 3 can often be guessed. (It is highly likely that a business is open at 14:00 local time) But you still need to look up an exact number to convert from local time to target time. So instead you just look up when they open (or what time businesses are usually open in that place).
Sure, but roughly speaking you know that 14:00 local time is probably okay for a business call, whereas 2:00 local time is probably not. You can get that information in a standardized way and the minor deviations due to local preferences and culture can be looked up or learned if needed. In contrast, with the other system there is no standard way of getting that information, except for using a search engine, Wikipedia, etc. The information not encoded anymore in the time zone, because there is no timezone.
Also, consider this: every software program would have to interpret per country what “tomorrow” means. I mean, when I’m postponing something with a button until tomorrow morning, I sure want to sleep in between. I don’t want tomorrow morning to be whenever it’s 8:00 hours in my country, which can be right after dinner. That means yet again that we need to have a separate source giving us the context of what the local time means, which is already encoded in the current system with time zones.
Not to mention the fact that it’s plain weird to go to a new calendar day in the middle of the day. “Let’s meet the 2nd of January!” That date could span an afternoon, the night and the morning after. That feels just plain weird and is not compatible with how we’re used to treat time. Which country will get the luxury of having midnight when it’s actually night?
I don't think we would entirely remove the concept of a timezone. Your computer would likely have some sort of proxy for "day time". Likely even some time offset from a reference. You would just talk in term of global time. But when you snooze an email "until tomorrow" your email client would still have some notion of "when I start work tomorrow" is.
I think you are sort of assuming that we will just be transported into this new world. But you have to account for the fact that language would adapt. With this mindset every change is a bad one. I agree that the transition would be incredibly painful. So painful that it almost certainly isn't worth it. But that doesn't mean that the other system is worse. It can be better, but too different to be worth adopting it.
Let’s meet the 2nd of January!
I agree that this is probably the biggest issue. It would take a lot of getting used to. But I'm sure that our language would adapt. And if this is the biggest problem I will take it over not knowing what times people are talking about any day of the week.