Banking records are by law confidential also. But the difference is one belonged to somebody running for president, and the voters right to know that the person running for president is not a crook.
Suddenly republicans want the affairs of private citizens that have not been accused of any crime, to be released to the public.
This would be like congress subpoenaing your bank records, and letting people know where your money came from, and where it went. And all without any legal reason, like evidence of a crime.