Spirit is also IFE-less. Also haven't seen it lately on Frontier.

You know you're a real introvert when you can do an entire 12- or 13-hour transpac with the IFE either off or on "flight plan" the whole time.^ There's reading, sleep, meals, and a lot of time trying to sleep but it being outside your circadian rhythm. If you have enough thoughts swirling in that tired-but-not-quite asleep mode and don't need to turn on the IFE, there's a good chance you're an introvert. Which in that situation can be advantageous.