Why cant we have just one Card!

Now days our life is full of so many cards. I am especially talking of the charge cards which are in a way , a financial instrument.

Firstly there are so many Credit Cards, debit Cards, and then ATM Cards, Top up Cards issued by various telecom service providers including for landlines and mobile networks. Then we have various kinds of discount cards issued by prominent retail establishments such as Reliance Fresh, Tata Card, Shoppers Stop and many more.
Why don’t we have one card which can be charged at various charge points in exchange for money rendered in cash, or through any other means. This card replaces currency and can be used to carry out various transactions being a pre-paid, cash charged card. The transactions should include topping up the talk time for all prepaid connections of all the operators, booking of air/ rail/bus/cinema tickets, paying bills of Electricity, Phone, making purchases at major retail outlets& Petrol pumps to start with, swiping the card to make payments of toll tax at various toll crossings, and also to transfer the balance to any other mobile phone connection.
Indian Banks Association & Cellular Operators Association can come together and adopt one card which should be honored by all of them. SBI or India Post, both of them have huge, all India reach to each and every corner of India can together issue Cards which can be made available at each and every branch of the State Bank and all the Post Offices.
Major Post Offices and Major Branches can provide top up/charging up facility against cash payment, whereas all other outlets can sell fixed value cards for Rs.100, 500, and Rs.1000/-.
This will make lives easy and convenient for all of us so that we can avoid carrying cash, live on just one card which can be used for variety of purposes, and make payments at various points of transaction.