Merchant account fees are diverse and go beyond just percentage-based transaction costs, encompassing various charges like monthly minimums, statement fees, and authorization fees. Additional fees can include AVS, PIN debit, voice authorization, batch, and online reporting fees, impacting the overall cost of payment processing. Merchants should be aware of these potential fees, such as retrieval, chargeback, ACH reject, gateway, and terminal-related costs, to fully understand their payment processing expenses.