Open Cup doesn't draw well anyways, including weeknights, and weeknight travel in Southern California is a nightmare, not too mention playing in a different county and pretty much attracting all O.C. fans and not many from L.A.
LA still outdrew Columbus.... 2,134 showed up. Perhaps if someone promoted the match, a few more might have shown up. In addition, I think it would help if the clubs discounted the tickets but I believe the geniuses at USSF don't allow that (even though they would end up with more revenue).