It's funny to see ARC just being described as a "data broker," which strongly implies that it doesn't play a role in facilitating the actual underlying consumer activity.

ARC and IATA absolutely do play such a role, as the financial clearinghouses for ensuring that travel agents (online and offline) and airlines can pay each other, and as gatekeepers/certification bodies for agencies to ensure these financial systems aren't abused.

Now, they absolutely do sell access to data to third parties, governmental and nongovernmental. But the reason they have this data isn't because they buy it to resell it; they are fully part of the funds flow for the underlying transaction. Whether they should be allowed to sell or share non-anonymized data on passenger records and prices paid is a very good question, but at the very least this is about as first-party as data gets.

https://www.altexsoft.com/blog/airline-reporting-corporation... describes some of these flows. (Here be dragons.)