Isn't there entire processes about "We suspect they doing something illegal behind the scenes so lets go and check"? Isn't that what search warrants for example is all about? Or senate/congress inquiry or whatever they're called?
With respect to inquries - if congressman X asks Sam Altman for the details of an algorithm at a congressional hearing, he is not obliged to answer. He can get his lawyer and argue the case - this happens and cases go to the supreme court to decide whether the question is in scope of the powers granted to congress under the consitution. The question has to be directly applicable to one of the responsibilities of congress, which are enumerated in the constitution. In practice redacted documents, limiting of question scope etc are discussed and worked around. Also in practice it's a bit of a political circus where most questions are for show rather than substance and you'll not really see them ask questions that would result in confidential information been given.