Banks have shareholders and are motivated by profit. They run advertisements that implicitly say they will be your best friend and help you achieve your financial goals. However, this is just not true. Their interested in maximizing their profits, and this can come in conflict with your goals. Banks charge higher fees, pay lower interest on savings deposits, and charge higher interest rates on loans. Also, one of the biggest sources of income for banks is what they term in their financial statements as non-interest income. This income includes a number of charges, like ATM fees, overdraft fees, and late fees. ATM fees, for example, average $2.97 per transaction in the U.S. On top of that, if you go to an ATM not operated by your bank, you can be charged an additional fee, averaging $1.72 nationally.
Typically, overdraft fees are $35 or higher. In 2017, commercial banks charged $34 billion in overdraft fees. These fees came from only 9% of their customers, almost exclusively low-income. Additionally, if the overdraft is not corrected right away, the bank will continue to charge fees until the account balance runs down to zero; they will then will close the account. Since the bank is already earning profits from interest they charge on loans, the overdraft fees are pure profit.
Many commercial banks sell their mortgages to Fannie Mae and Freddie Mac, so they must conform exactly to the rules of these institutions. Your mortgage could end up being owned by anybody. A credit union might be a better choice. They will keep all or most of their mortgages, so they are more flexible on their requirements. If you do not have perfect credit, a credit union is more likely to give you a mortgage than a commercial bank.