Very good point but i believe the cash in hand doesn't account for all the money you have.

There are many facets for accountability. And I don't think that any middle class person having more cash in hand while exchanging his cash could potentially prove that his money is accountable because there exist some form of money which he has given to some other person or may be has invested in some business.

My point is by totalling out just the amount of cash maybe 5-10k rupees the income cannot be accounted.