Pity for DTR that things seem to have changed.
In '98, I was in the Bay Area on an extended business trip from the UK. Popped into a Club at Palo Alto Airport (about 25 miles S of KSFO) and was told I needed to go to the FAA Office at San Jose, to get the "Temporary Airmans Cert".
Once there, I was dealt with very efficiently by the FAA staff, and the whole thing took about an hour.
The airspace around the Bay Area is crowded and quite complex (even for someone who normally flies in SE UK) but I found that if you were "on the ball" on the radio, VFR clearances were readily given to, for example, cross the KSFO overhead at 2000' (with all 4 runways in use below you
- not something you could ever do at EGLL!!), then route out over the Bay for an overflight of Alcatraz and the Golden Gate - fab
I flew a 172 at Sundance Flying Club, Palo Alto Airport (who had some PA28's aswell, and were very friendly) - was signed off solo after a 1.5hr check.