Southwest didn't buy the option either until after the Lion Air crash: In manuals that Boeing gave to Southwest Airlines — the biggest operator of both the MAX

Southwest didn't buy the option either until after the Lion Air crash: In manuals that Boeing gave to Southwest Airlines — the biggest operator of both the MAX and 737s in general — the warning light was depicted as a standard feature just as it is on older 737s, according to Southwest spokeswoman Brandy King. After the Lion Air crash, Ms King said, Boeing notified Southwest that it had discovered the lights did not work without the optional angle-of-attack indicators, so Southwest began adding the optional feature too. (quotes from https://www.abc.net.au/news/2019-05-06/boeing-knew-737-problems-before-lion-air-ethiopia-crashes/11084326 https://www.abc.net.au/news/2019-05-06/boeing-knew-737-probl... )