What's the deal with you Americans and your magic numbers?

So you have your Social Security Number that you can't give for fear of someone impersonating you, your Credit Card Number you cannot give for someone might steal from you and now you tell me you can't even give your bank account number.

So you have all theses numbers you have to keep secret because they are the gateway to someone ruining your life, yet you still have to communicate them routinely to a number of institutions in order to function in society. Isn't that a bit crazy?