ontheroad, since you bring this up, I have a suggestion:

Why not putting a casino on the plane? This may be the only way the major airlines can compete with SWA... Since the profitable customers from the majors have deeper pockets (paying full/B/F fare), they are potentially bigger gambler. OTOH, SWA flyers are the cheapies with your analogy, they have smaller budget. So, SWA can only put 5c slot machines on the planes whereas minimum bet on AA/UA/DL/NW/CO/US is $1.