Southwest airlines doesn’t do assigned seating. Instead, they have a fancy alpha numeric system that prioritizes boarding order by check-in timing.
I was seated on a plane the other day when a woman walked on and asked the flight attendant where she could find seat B38.
Flight attendant: Oh honey, you can pick any open seat you’d like. We haven’t assigned a seat in 40 years. It’s a bit like going to church… just with a different kind of baggage.