This study explored the issue of whether the use of the Automated Teller Machines (ATM) as a service delivery tool in the banking industry of many developing countries has achieved its intended objective of increasing the effectiveness of customer service provision and reducing the workload of bank tellers. The purpose is to understand customers' behaviour towards the use of ATM as a banking service delivery tool, and the influence of such customer-usage behaviour on the banks' human resource capacity building, in terms of employee workload relief and performance. This is because most banks in sub-Saharan African countries have introduced the ATM in bids to satisfying customers' service needs and making the work of employees easier. Data was collected using questionnaires that were administered to bank customers who use the ATM facility, as well as bank managers. The findings showed that though most bank customers who use the ATM services perceive the ATM as a convenient, reliable, accurate and suitable service delivery tool for their banking transactions; they still underutilize the ATM's service capacity by choosing to go to the banking halls to make cash withdrawals of amounts that could be obtained from the ATMs. It is also found that by virtue of this customer behaviour of not using the ATM's to their full potential, the relief that it is expected to provide bank tellers is not realized. It is concluded that because of customer behavioral challenges to the effective utilization of the ATM technology, banks in developing economies not benefiting from its full potential as a customer service delivery tool, and also as a strategic workload reliever for tellers who service customers inside the banking halls.