I also live between SAT and AUS but usually try to commute from SAT to DFW. The employee lot is really convenient at SAT. It’s been hit or miss for me. I’ve had to drive some of the time but that’s mostly because I see the loads look terrible (due to holidays or cancellations) and decide to sleep in and drive instead of worry about flying.
For reference on AA it’s pretty normal for all 10ish flights to have 10+ nonrevs listed. Granted I’m at a regional so I’m way down the list. I haven’t resorted to SWA to DAL yet though that is an option. If I was based in Houston I’d probably default to driving.