Raising fees on small-ticket debit purchases could hurt self-service kiosks, such as DVD rental kiosks, which "benefit from debit-card acceptance, " Mr. McCrohan wrote.
Visa and MasterCard wouldn't directly comment on Mr. McCrohan's conclusions, but have said they would change debit-card fees, known as interchange, in response to new federally regulated caps.
Mr. McCrohan wrote in his note that the companies' price increases could be meant to help their partner banks make up revenue they stand to lose under the new caps.