When people ask why banks don't provide foreign currency exchange services, there are various reasons behind it. The primary reason may be the bank's insufficient foreign exchange reserves. Banks need enough foreign exchange inventory to support foreign exchange business. Insufficient inventory, naturally unable to meet the customer's exchange demand. Secondly, if the bank observes that the customer's demand for foreign currency exchange is not strong, it may think that it is not cost-effective to invest resources in this service and choose not to provide it. In addition, laws and regulations also play an important role. Due to the restrictions of local laws, some banks may not be able to carry out foreign currency exchange services to avoid the risk of violation. Finally, banks will also consider risk factors in their business strategies. Foreign currency exchange business may involve exchange rate fluctuations and market uncertainty, so banks will have reservations about managing risks. To sum up, banks' refusal to exchange foreign currency is determined by their inventory management, market demand, regulatory constraints and risk considerations.