India's GST challenge makes Donald Trump's tax overhaul look easy

The challenge is daunting: Convert an economy of more than 1 billion consumers, 29 states, 22 official languages, 9 million businesses all operating under a spider’s web of taxes, arcane regulations and competing political ambitions into a unified common market.  But that’s the goal as India gets ready to roll out a goods-and-services tax after a 10-year battle to win over the country’s power…