As far as smart economics go, it's in the best interest of SAA to collect the funds just as TravelinWilly states. They are a business and needing to do whatever they can do to up revenues on otherwise "money left on the table". Airlines struggle these days, and charge for everything else... so it amazes me that they wouldn't do it. I've flown to Hawaii a few times and it's definitely been offered at the gate on multiple airlines -- sometimes I've taken the offer, other times I have declined. Lets face it, collecting those extra monies before departure costs the airline nothing... there is no added expenses for upgrading those passengers since they were going to be on the aircraft anyway (so they would have to have the customer service contact at the gate, service in cabin, luggage handled, etc).

And it's in an airlines best interest to expose as many travelers to their biz class for it's word of mouth that gets many of the passenger seats it booked in an upper class. And the next time someone who's enjoyed the luxury and comfort of biz class is about to book another trip, you bet they are going back to their memory and probably realizing that its worth the price for their comfort vs. sitting in economy. Its like once you drive a Mercedes its difficult for you to drive a Yugo.

Its all about price yielding. Airlines/Hotels will charge as much as they can at the highest prices and then discount when they think they cannot fill seats. It's a game with a certain strategy that sometimes they win and sometimes they lose.

For those that don't think it's fair... go seat to seat and see the major price differences people paid for their same exact experience. It doesn't change, and the price difference is even greater in economy. Same thing at a hotel, knock on each door and find out what people paid for their same room on the same night to get the same bed with the same sheets. It's no different. Obviously there is a cost per guest in a hotel situation (housekeeping, etc)... but once that's been met it's only revenue to the books. So they are stupid to not fill the hotel at a discounted rate with surplus inventory. And airlines are just as stupid to not take advantage of it.