banks have contracts with governments, mints, royalty, feds to only handle legal tender
That is your continual unfounded claim. Please provide a cite that all banks in the world are prohibited from handling anything other than legal tender.
Just an example of a bank which would appear to be violating this "legal tender only" secret contract:
http://www.icicibank.com/Personal-Banking/investments/icici-bank-pure-gold/index.page