GST works at so many levels. If exports, production and transport are benefited, so will GDP. Much lower stock in warehouses and transit saves huge sums (100s $ billions), so prices should fall. Multiple slabs should not be the reason to slam GST. All Govts try to maximise taxes where people can afford it. Petrol, cigarettes, alcohol always have higher taxes, while basic food, clothing, education and health services attract little or no taxes. In India cars, air conditioners, home appliances, etc are considered a luxury, which is not really the case. Any case, 28% tax is too much, counter-productive & hurts the middle class. IMO, the standard tax should be one rate between 12% and 18% (say 15%) and price bands, e.g. hotel rooms should be done away with.
Talk that GST would boost GDP growth by 1-1.5% rubbish: Bibek Debroy