as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
why is there so much variability on interest rate accounts
user
pay attention to nickel-and-dime charges (atm fees, low balance fees, limit on atm transactions per month, charge for human teller transaction, charge for paper statements or tax records).  consider that a financial company will spend on the order of $100-500 to sign up a good customer.  are you getting this in a cash bonus, competitive high interest rate, reasonable other gift, or advertising directed at your eyeballs?  a variation in rates less than 1% easily fits into a marketing cost and there doesn't have to be any other magic to it.
assistant