If I am unable to pick up groceries for the lack of cash, I can surely choose to order it online (using a credit/debt card). A vast majority of Indians cannot.
A majority of Indians don't have access to banks either. They will be forced to exchange their now illegal currency with the help of agents who would charge them 50 to 60%.
Most of the ATMs are out of cash. There are huge queues at banks; most of them are giving away Rs. 2000/= bills. Amusingly, if you were to give the new bill to a shopkeeper chances are that he'd refuse to tender the change back as the closest denomination to that is a Rs. 100/= bill.
Statistics reveal that only 6% of the black money is in the form of cash. As such, the argument of declaring higher currency notes as illegal tender in order to curb black money in unconvincing.