That answer is easy: just like the indians, steroid-free baseball, and cheap gas, they're gone. When I arrived in SoCal almost 6 years ago, we had several cool spots we'd drive to and photograph trucks. Now, that list has shrunk down to just a few. Housing developments, buildings, and other types of construction have darn near eliminated most of our popular Orange, LA, and Riverside County locations.
I'm in San Francisco right now and we just pulled up to a vineyard and started shooting. I miss those days.
The photo of the H1 was taken in Aliso Viejo and had the beautiful backdrop of the Saddleback mountains. That spot is now a parking structure with buildings all around it....bummer.