The main reason is that banks want to be charge negative rates (charge you money for keeping it in the bank). The reason they are having trouble is that one can move the cash out. Thus restrictions in cash withdrawals.. etc.
So it is all a matter of greed.
Don’t fall for this BS.
Please note that we are being sold this bill of goods much like ‘Net neutrality’ – fooling people in to buying into tyranny as it being somehow to their benefit.