It's not a global constant. Across Central and Eastern Europe it's quite common to work 7am-3pm. You have half the afternoon in the sun at any time of year to enjoy. In winter it's a bleak commute to work though.

I mean, in a way, you are changing the end of the work day (the work day will end a hour earlier in the previous time zone at one shift, and one hour later in the previous time zone at the other shift), it's just that the time zone shift is the mechanism we use to do it.

If we use the approach of having the workday end at 5 PM during one half of the year, and 6 PM in the other half, people have to ask themselves "Are we in the 5 PM half, or the 6 PM half?" This confusion will probably last for a few weeks, similar to the confusion when a year changes (I write the old year for at least a month).

On the hand, changing the clocks is a one time change, and then you don't need to constantly check which half you're in.

winter is 6 summer is 5. if you have to think about it it means you are oblivious to which season you are in.

Presumably, there would be specific date that this change will happen. But the seasons don't change instantly from summer to winter on a specific dat, they gradually change over a few weeks, where the confusion I talk about will still occur.

Or in Hawaii

Or have the company just define and post business hours that work for them, like all retail companies do.

Or arizona

Also I know Colorado is mountain and it's always either -6 or -7 but on any given day I have to look up which it is. It's not a reflection of my intelligence.

If you are in Hawaii you are near enough the equator that the day length changes is negligable anyway so having a offset is pointless.

It's also somewhat problematic: the above poster made a lot of assumptions about work day, but they're less and less true. Empty nesters, people without kids yet, childfree folks, all that rules out the school schedule (looking at the size of the school in my town, it's a small minority of people who have school aged childrens).

Then the 9-5 work day. Tradefolks often start much earlier. People working late shifts at restaurants and other service industries are very unlikely to do simple 9-5. People in tech are all over the place. "Early bird gets the worm" because if you're not at the default or earlier, you're basically fucked: hope you didn't need to sleep 7+ hours after that night shift, because you certainly aren't going to when the neighbors let the dog out to bark!