Originally Posted by xliioper

LAS is somewhat of a domestic outlier market as DL will often have larger differentials due to ULCC competition. Presumably, this is a roundtrip booking as nominal difference on one-way fares is $65. Differences on roundtrip BE fares (with Sat stay) can get as high as $80 each-way on both ATL-LAS and DTW-LAS with BE roundtrip fares starting at $239 and Main starting at $399. There's also a hostage hub effect involved here. If you check fares from nearby airports that are not hostage hubs (like CLE-LAS and CHA-LAS), fare differentials are a more reasonable $45 each-way.