Every new move, whether for the good of society or for the good of politicians, starts with a deception.
The BMC's rather good idea with regards to the ban on plastic bags in Mumbai, along the lines of Pune, is meeting with a whole lot of sly manoeuvring from shopkeepers. As per the new rule, shopkeepers cannot put their wares in those amazingly thin plastic bags when they sell stuff to people. The bags in question are those that drape themselves around you at the slightest breath of wind, or sink to the bottom of gutters and drains and are so thin that you can't even see them when they're wet.
The BMC is sending out random patrol teams, and the bigger news is, that customers seen carrying the aforementioned bags (or indeed, anything thinner than 50 micron) will be fined on the spot! Shopkeepers can also get off by saying that the customer insisted on a bag, though that should ideally not fool anybody.
Hence, shopkeepers have carefully hidden their carry bags under boxes or behind the refrigerators or masquerading as containers that carry soaps, toothbrushes et al. When a customer asks for a bag, they look left and right, up and down, inside and out, and swiftly whip out a bag. Having dumped all the purchased material in it, they politely ask you to scuttle off and not be seen again.
Other places have come up with their own business take on the matter. Places like Sahakari Bhandar handing out big bags of a thickness visible even to a blind naked eye have decided to encash on the no-plastic bag rule by charging an additional Rs 2 per bag they give. Be warned that bags above 50 micron should be given free with the items you purchase, so if anyone asks you to pay extra for such a bag, tell them to fuck off.