Offer your thoughts or opinion on the input financial query or topic using your financial background.

Why don't banks print their own paper money / bank notes? 
Are you talking about printing up more of the same kind of bill, or printing up a different kind of bill?  You'll have different answers based on which one you mean. If it's a different kind of bill: Governments don't like competition in this matter. In US history there are examples of the government shutting alternative currencies down.  A recent run at an alternative currency is the Liberty Dollar.  The similarity is not lost on BitCoin or even Chuck E. Cheese (last one is a satire, but I did worry for a second as I still have a bunch of those tokens!). If it's the same kind of bill: The currency is a tool of the government (in the US) and it does the sourcing for its production.  There isn't a whole lot of reason for others to get involved, really.  It's special paper, special plates, special presses, special everything, and doing it in one place ensures some consistency of product.  There aren't any compelling reason to open up another manufacturing channel to produce exactly the same product. There's no real economic benefit for banks to print their own money.  The larger ones play a key role in shaping how much is printed, but actually printing the bills is an offshoot of this.