Drones can be economical for smaller areas, such as villages as mentioned in the article. For larger areas spanning hundreds of square km/miles, small UAVs won't do. Long range fixed wing UAVs or regular planes equipped with hi-res cameras or even satellite imagery are more suited. In the end it's a question of which approach is more fit-for-purpose, given the requirements and constraints.

In a country like India, cloud coverage during the rainy season can last for months, rendering satellites (unless you use something like SAR with false color composites) effectively unusable. Drones may not be able to fly during periods of rainfall, but can still be operated in daylight during breaks in weather.