Google hooks into the systems that want Southwest to pay, it's not directly making that decision.
(This thread started with me arguing that "it costs money to be there" was not the reason Southwest flight prices aren't in Google.)
So the way this is working is: Google, Hipmunk, etc. use GDS for queries, and then send customer to airline to book? Does GDS have any ability to sell tickets?
Has Google tried to scrape data directly from Southwest website and Southwest won't let them? Or is it just that Southwest will not provide APIs to make it easy for Google to pull the data?