This is a conscious decision by Southwest, it is willing to trade off the lack of exposure on the booking engines for not paying any commissions and keeping 100% of it's fares as revenue.

More or less, yes. Proper SABRE integration came last year, and only for businesses.

https://skift.com/2021/08/06/southwests-expanded-partnership...

Looks like Apollo and Amadeus came in 2020.

https://skift.com/2020/05/19/southwest-airlines-expands-corp...

https://www.businesstravelnews.com/Distribution/Southwest-Go...

So if you use "Kayak for Business" you can book Southwest, otherwise you can click through on the ads that Southwest runs on Kayak. And, yes, it was a deliberate (Herb) choice. So was not being an IATA member and not participating in the IATA clearinghouse. The upside is less overhead the downside is less resiliency. You don't need to care about these things so much when you're flying a regional jet on mostly intra-Texas routes out of an airport that only allows short flights. With a full-sized airliner and an international route network things look a little different.

https://www.iata.org/en/about/members/airline-list/?search=W...

Um, Southwest participates in the IATA clearing house. You put up the wrong list. Here is the right one: https://www.iata.org/contentassets/82a24c7a736142b6bd18e20f7...

And now for some industry education. You can participate without being an IATA member. Southwest likely started when they started flying internationally in 2014. You practically can't be an airline with international flights without participating. IATA runs the global clearinghouse.

Notably, IATA does not run the clearinghouse for US domestic (and for foreign airline tickets purchased in the US.) That's ARC (Airline Reporting Corporation.) Southwest is also a member there.

OOf. I did intend to link to the list of IATA members, but I naively assumed that because Southwest does most things in house and does not have any interline agreements that they would also have no reason to be party to a clearinghouse. Of course now that they started pushing reservation stuff to various GDS platforms (beginning in 2020 give or take) they have a use for a common settlement method.