SEC bought access to over a billion airline records to track travelers, no warrant required

How is this not unlawful search?

I understand that because the use of and purchase/sharing of this kind of data (which for the purposes of my arguments includes any data broker data, including the data from Flock license plate readers) is not considered illegal due to a lack of consumer protection laws. But how is the government acquiring and using this data not considered a subversion of due process?