These days, travelers may be forgiven for assuming the U.S. airline industry is eventually going to become one big giant code-share.

Southwest Airlines, however, has always seemed to march to a different drummer in many ways, not least of which with their “Keep It Simple, Stupid” model of having all one plane type, no real catering, and no pre-assigned seats.

Which makes today’s report that Southwest is planning to bid against Republic Airways for Frontier Airlines more than a little surprising.

Now, I’m not an airline analyst, but Southwest and Frontier, while both considered “discount carriers,” are very different airlines. For starters, Frontier doesn’t fly the same Boeing 737s used by Southwest, they use Airbuses. In addition, Frontier uses the more standard airline model of $150 change fees for tickets, they pre-assign seats, and while there are no free peanuts, they sell sandwiches and other food on board.

Perhaps most complicating, unlike Southwest, Frontier has interline agreements with other airlines. (To translate the jargon, “interline agreements” means that an airline can check baggage and accept tickets from other carriers.)

Now it is possible what Southwest really wants from Frontier Airlines is their route structure and gate slots. But scrapping the planes and indeed most of the operational structure of Frontier would presumably be neither easy nor inexpensive.

And if Southwest operates Frontier as a subsidiary, would they accept Frontier tickets and vice versa? (And what would that do to Frontier’s arrangements with other airlines?)

As I have written before, I have slowly come to appreciate Southwest’s style, simply because it seem to create less problems. But “simple” doesn’t seem to be the word to describe this potential takeover.