Reciprocal lounge access is only relevant to those who would not get access with their class of travel. In any event, it is an adjunct to the FFPs of the member airlines. As the prevalence of non-alliance cooperation agreements demonstrate, allowing people to earn points/miles on other carriers is a lucrative money-spinner. Which means it falls into the category of things that advantage the members of the alliance financially, hence why it is offered. Any pax benefit is a spin-off which is cunningly marketed as if that was the main reason for doing it. It's not. It's an illusion.

When it comes to the crunch, will you be able to get the LAN ticket desk to reissue a BA e-ticket prior to a BA codeshare (ops by LA) departure from SCL? Of course not. No money in that for LA, so it doesn't do it.

When you come to measure the boasts of the OneWorld marketing boys and girls ("... or please see one of our OneWorld Alliance partners" ) against the actual delivery, you'll find it seriously wanting.