After a long break (15 years or so), I have flown on a bunch of flights all recently domestically within the USA and I discovered Southwest. Looking at the perks they offer such as picking your own seats and two free checked bags, what I don't understand is why doesn't everyone fly Southwest.
So my question is what is it that other American airlines such as American or United offer that Southwest doesn't? The only thing I can think of is that other airlines have many more destinations including international. Do they have extra legroom in the economy classes without having to pay extra? Are there more menu choices? Do they just have a lot more flights allowing flexibility in time? Insight from seasoned flyers is solicited.
Just to clarify, I am not looking to spark a debate or start a discussion. I am only curious about (objective) travel perks other airlines offer compared with Southwest.