It is not unusual for home buyers to feel that the lender is being very critical during the loan approval process. The buyer is required to provide all kinds of financial information, and then the lender asks for more. If this is your experience, and the process seems discouraging, remember that none of this is personal!
Some lenders have more stringent requirements than others, but every lender requires a substantial amount of documentation on a mortgage loan. They must verify employment, credit history, and recent financial transactions involving your liquid assets. If your Visa payment was late, they may ask for a letter explaining why. If you are self-employed, they will ask for tax returns from at least three years and probably a year-to-date profit and loss statement.
Government regulations require mortgage companies to document everything. And while the loan officer may know that you are a reliable risk, the underwriters must be able to defend the loan to a federal bank examiner or auditor.