As someone that flies both UA and WN all the time, I'd actually argue WN's pax on the whole are more sophisticated travelers. The largest driver would be the fact that you actually have to know about Southwest and seek out its 800 number or website to book a ticket.

UA may have a few more folks in suits, but the lowest tier of UA un-frequent-flyers is much, much lower than WN's in terms of sophistication. These are folks that only know Expedia or Hotwire or other intl equivalents and bought UA because that ticket was cheapest. UA also has boatloads of unsophisticated intl travelers that are connecting domestically. These folks are often traveling with families and have no seat assignments for any of them. They're the last on the plane and completely clueless to air travel norms. I could go on and on about the archetypes of air travelers you see as a frequent flyer, but that's a different thread. : )