On that large scale that you're talking about re: Wyden - it's called "congressional oversight". Wyden does this a lot because, as that letter you linked noted,

On that large scale that you're talking about re: Wyden - it's called "congressional oversight". Wyden does this a lot because, as that letter you linked noted, he's the ranking member of the Senate Finance Committee, which has jurisdiction over CBP (as well as over the more directly finance-related issues he's written on). Note also that the letter is printed on Finance Committee letterhead, not on his own - he's writing on behalf of the committee, not only out of his own personal interest.