Why do some places give interns more responsibility than other places give their FT employees

Several interns have underwritten several millions of dollars in loans, either individually or as part of a team, yet some lending institutions don't give their employees any underwriting responsibilities and it is really bugging me. Why do some companies do this? They give shit jobs for people with very minimal responsibilities while others give the same jobs with actual responsibilities. It seems that these places are always the ones with high turnover.