India faces a variety of institutional and business barriers to more-rapid deployment of Internet access services, some of them related to business models and the cost of building networks to serve customers with average spending of about US$2 a month. But regulations, taxes and zoning arguably play a significant role.
One might argue that making lots more spectrum available, free or cheap, would dramatically change the cost side of business models. That tends not to happen in India, since the economic rent from leasing spectrum is seen as so lucrative for units of government.
Spectrum sharing might be one way to reconcile both objectives: better business models for Internet service providers; faster deployment and lower prices for consumers and yet incremental revenue for governments.
The broad movement is to free up licensed but unused spectrum in an efficient way (enabling sharing), as the traditional methods (clearing users and then relicensing) take too long and cost too much.