Data in India is really cheap. You pay <$7 for 30GB of data and the speed is not bad at all (about 20-30Mbps)!
[0] https://data.worldbank.org/indicator/NY.GNP.PCAP.CD?location...
[0] http://www.livemint.com/Politics/AvHvyHVJIhR0Q629wkPS5M/Indi...
Smartphones are extremely important part of India's way of life as almost everything else is regulated to death. It is a ray of light for most poor people and you will find people who might not have a toilet but will own an android smartphone.
The plan you mention, is about 11% of the average salary in India.
Even though it's cheaper in absolute terms, it's still more expensive in relative terms.
I actually saw this mentioned in a recent UX talk by google: the salary differences end up making internet a lot more expensive for the locals in India, Indonesia, etc, to the point where some apps actually show how much they'd use (eg: Youtube shows the size of a video before downloading).
People still micro-manage they available data because of how expensive it feels to them.
Copying this, almost all carriers are in various stages of decommissioning their 3G services and migrating to 4G countrywide. So, even in remote corners of the country, 4G is more widespread now but the speeds are not always 20-30Mbps across the country.