It’s also not really true. At least in many countries bank balances up to some amount (eg $250,000 in Australia) are insured by the federal government.
But outside of that many things could cause the bank to lose your money. And there wouldn’t be a recourse for it.
I suspect you're confusing money and cash - they're two distinct things. I would be incredibly to learn that my bank had anywhere near the amount of cash stored compared to the amount of money deposited there. Cash has storage costs and pays a 0% return where deposits with a central bank have historically paid higher than that. (This isn't universally true.)
But outside of that many things could cause the bank to lose your money. And there wouldn’t be a recourse for it.