Exactly right.
Every business has to trust its employees to maintain certain information confidential, and the best way to demonstrate the importance of this is by respecting the confidentiality of a prospective employees salary history. Let them be the judge of whether or not to accept an offer.
Besides, the company should establish the value of a job based on industry norms without regard to any one individual.
I disagree with this.Industry norms
for my industry are very, very distorted thanks to H21B visas, where the the big companies post ridiculous job requirements and use that as justification for saying "there aren't any US citizens to take the job" and getting the visas for foreign labor that will take the job at that price…
I can imagine that this is the case with other industries where they can get away with it.