The BART surcharge is just for using the SFO (Airport) station. The BART fares to the station before SFO (San Bruno), and the one station beyond SFO (Millbrae) are considerably less.

This surcharge may have something to do with the extra cost of building that airport BART station. When it was being planned, BART management wanted to build the station about a mile W. of SFO, along its planned right-of-way. That would've required a bus or other type of shuttle to get riders into SFO. Then SF Mayor Brown, who had built a powerful political base, as a former State legislative leader, said, "NO!!!" and insisted that the station be at SFO! He and many BART users (me when BART skeds align with my flight skeds) won. Now that I qualify for Senior fares on BART I get a good discount over the posted, adult fares.