If the bank pays interest they make that money by loaning money to someone. They don’t pay you to warehouse your money in the bank. With this is the assumption

If the bank pays interest they make that money by loaning money to someone. They don’t pay you to warehouse your money in the bank. With this is the assumption that they can’t immediately give you your money back because they don’t have it. Checking accounts are different so the presumption is that money is just sitting in the bank doing nothing because they can’t predict when it will be spent. Of course this isn’t how banks really work because reasons.