These two national policies aren't equally difficult: India extends across about 29° of longitude, while China extends across about 61°. The natural size of a time zone is 15° of longitude, so without political considerations India would include about 2-3 time zones, while China would include about 4-5.
I've heard there's some pushback against the Chinese policy in that some people in the west keep an unofficial local time which is widely understood and quoted (though presumably not for things that are sufficiently official or relevant to other regions). Apparently there's currently an ethnic conflict over the time zone status in Xinjiang:
https://en.wikipedia.org/wiki/Xinjiang_Time
Maybe this conflict has now been pushed underground by force?
> In 2018, according to Human Rights Watch, a Uyghur man was arrested and sent to a detention center because he set his watch to Xinjiang Time.
We still do not. China and India are examples of large geographies spanning across a vast amount of longitude and yet each are a single time zone. Time zones are a political entity only, an unnecessary complexity. The absence of time zones will not halt business or communication over long distances.
> For most people talking about time in their day to day lives it's far more useful to communicate a relative time of day
People have done this for thousands of years without modern chronometers. Examples: dusk, dawn, morning, midday, afternoon, evening, twilight.