Financial institutions (banks) are responsible in handling financial issues, records, accounts and income of individuals, companies, churches and organizations. They respond promptly according to your demands on your accounts, they also have zero tolerance for fraud and are very security conscious, security intelligence and anti financial crime expertise but they've policies of not collecting dime from customers accounts yet banks are most wealthiest institutions on earth.
How do they make money?
* mortgage - using some billionaires account to buy housing properties and leasing them
* estate and lands with same patterns
* SMS alert charges
* Transfer charges
* Syphons dormant accounts or dead people accounts that are inactive with enough money in it.
* ATM and investment cards
* sales of currencies like dollar to naira
* preparation of international documents
* savings people's valuables like gold, certificate, court documents, WILLS, and so on.
This is what makes financial institutions very wealthy.
Here in us there are some banks who has a high maintaining balance if you forget to maintain the amount they will continously deduct it to your account until you don't have enough money. Although it is written and has been in their t&a before you join the bank still it is kinda hard to maintain because of the inflation right now, when you don't have other resources. Other than that banks earns in their credit offers and loans.