Last startup I worked for hired a Nepal-based QA person. There was a bunch of calendaring and daily/weekly charts in the apps, and she found bugs in _everything_.
I make sure to test with Nepal time whenever I'm testing date/time stuff now.
And, of course, there's the (hopefully apocryphal) story of the French initially referring to GMT as 'Paris time minus nine minutes and twenty-one seconds'.
As it happens, this story isn't apocryphal at all! One can readily find the original law, which was enacted on March 9, 1911, and published in the Journal officiel of March 10, 1911 [0]:
> Article unique. — L'heure légale en France et en Algérie est l'heure, temps moyen de Paris, retardée de neuf minutes vingt et une secondes.
The decree which finally replaced it was made on August 9, 1978, and published on August 19, 1978 [1]:
> Art. 2. — Sur l'ensemble du territoire de la République française, le temps légal (ou heure légale) est défini à partir du temps universel coordonné (UTC) établi par le bureau international de l'heure.
When I built a live clock for some new CasparCG based graphics for a major TV program out of singapore some years back, a colleague reviewing it in London tried to trick it with a Nepal offset — apparently they’d run into an issue with the Viz system they used in 2015 when there were a lot of lives from Nepal.
RealLifeLore just had a video about time zones in that area of the world, there's an area between New Zealand and Hawaii where you can go north/south and jump an entire day.
There isn't a perfect geographical width for time zones. So humans pick something to define the boundaries between time zones. And making boundaries on a map is political.
To some extent a compromise between solar time and political and economic realities. For example, the Eastern Time Zone in the USA stretches almost to 90 degrees West, reflecting the East Coast's powerful pull on that part of the country.
A lot of it was GE's fault at the time, specifically. GE wanted facilities in New York, Cincinnati (OH), and Louisville (KY), among others, to all be in the same time zone and had the economic power at the time to lobby the railroads and the cities to make that happen.
Friend told me that Indiana not adopting Daylight Time until quite recently was due to a struggle between broadcasters, who of course wanted to match their networks, and drive in operators, who wanted it to get dark earlier so they could start the shows earlier.
Yeah, Indiana also had an interesting three way battle between Chicago, Louisville, and Indianapolis. A lot of population near Chicago getting Chicago broadcasts (Central), a lot of population near Louisville getting Louisville broadcasts (Eastern), with the state capital Indianapolis interestingly caught up in the middle (physically closer to Chicago, but maybe emotionally more connected to Louisville) which itself as a city eventually after a lot of back and forth settled on Eastern time following Louisville's lead as one of the westernmost cities in the timezone.
Indiana's Daylight Time mistakes were fascinating. It wasn't that the state didn't adopt it, it was that originally the state allowed it to be a per-county decision as timezones have always been in Indiana. At one point in time if you were traveling I-65 which is nearly due north/south between Louisville and Indianapolis you could experience four different timezones (CST, EST, CDT, and EDT) and which ones agreed with each other obviously depended on which month you were traveling. Since Indiana went state-wide Daylight Time and Indianapolis decided on EDT once and for all, all of I-65 today is EDT I believe, but it is still strange to remember the years where that wasn't the case.
(ETA: one of the underappreciated homogenizing factors here has been the modern cellphone. People would get really confused if their cellphones hopped an hour back/forth every so many miles as you passed county lines. In the eras of paper maps and hand-set clock radios in cars that would have mattered a lot less.)
In Europe, a huge driver for standardization of timezones into "reasonable" slots was railway traffic, including cross-border traffic.
Railways are extremely sensitive to exact time and, indeed, the very concept of unified time across the entire region or country only started developing when railways expanded across Europe. Prior to that, individual towns were happy with their own local solar time, but once railway connections were introduced, time irregularities would cause chaos at best and carnage at worst. That led to introduction of unified railway time which developed to timezones as we know them.
Railways aren't as prominent nowadays as they were 100-150 years ago, and countries like Nepal and India don't have extensive, frequently used cross-border railways anyway; any cross-border traffic is sporadic and mostly freight. So there is one fewer reason to cooperate with your neighbors when it comes to time-related issues. Trucks can take weird timezone changes just fine.
That far south it only varies by a couple of degrees. It does wreak astronomical havoc in Mumbai, though, where the Sun will sometimes be way in the northeast at noon.
because humanity never understood time properly.. so all these facades making it look "simpler" while actualy a lot more complicated.
long time ago there was a special `$ man date` -like page in linux which went into long explaining many "amazing" things about calendar stuff, like whoever feudal in 1553 deciding that certain week was bad and striked it out of his and his country's calendar, or another one that liked certain month and decided to repeat it...
I make sure to test with Nepal time whenever I'm testing date/time stuff now.