a) you have an IQ of 160+ but most people don't. Most people are too dumb to clean their ass properly. I thus believe it will make all the difference in the world when the nominal interest rate on savings accounts and such, becomes negative. Adjusted for inflation? Most people don't even know what that means. If people see the negative interest deductions on their account, no matter how small, the stampede will start. When Joe and Jane Doe see a -0.01 EUR interest payment in their account it will commence.
Nominal interest rates on checking accounts won't be negative.
People would simply take the money out of the bank. Until you can enforce negative interest rates of cash (physical paper currency) that will remain an option. Banks will simply absorb the impact by other means. They could raise the fees on checking accounts by 1 euro per year as an example, or lower the interest charged on debt products to grow their balance sheet that way and eliminate or reduce the amount of funds they need to transfer to the ECB.
The only people who will see negative interest rates ARE SOPHISTICATED financial types (bond purchasers, pension funds, accountants for major corporations, etc) who already understand the concept of real returns.
Are you the same D&T who elaborated about money laundering implications awhile ago?
Yet don't realize that cash withdrawals are not practically possible due to regulations? In most countries on this planet amounts over 1000-5000 get you in hot water, with deposits being even worse. And deposits you need to do, because cash payments are also not accepted for most transactions.
So no, people cannot have most of their money in cash outside of bank accounts, unter their mattress or whatever.
True, they will absorb if for awhile but not forever, if primerate is -1% you will have a deduction on your checking account for sure.