Mount Diablo is, as you're aware, a one-way street, and in the block between Salvio and Willow Pass, is lined on both sides with angled parking spaces. It's also a 25mph limit. While I have no doubt that you are a very experienced driver, I find it astounding that you consider it safe to blast along that street at around 50mph, because the parking spots (on the left, anyway) are sloped away from the centre of the street, leading to a need for anyone backing out of them to feed the car with fuel, since very few cars have sufficient torque to reverse creep uphill at idle. This means the foot is less than available for the brakes. Add in the rather restricted visibility (since most cars are designed with little thought to backing up, and SUVs are a popular class of vehicle around here) and you will rapidly see why the folks backing out of the parking spaces have right of way; they are FAR less able to see or to respond to hazards than someone driving along the road. Moreover, a small sports car like the Scion tC I drive will be well-hidden by other cars (a fact I can actually verify through using Google's street view, since one of the vehicles parked along there when the street view car went past was a Scion tC) and thus would appear unexpectedly when backing up.
All of which is to say: you were driving FAR too fast, particularly given the fact that it had just started raining, and we are BOTH lucky that I slammed my brakes on as soon as I saw something unexpected. Me because had I not done that, you WOULD have hit me and almost certainly totalled my vehicle (for the UK readers: write-off). You because you would have been found 100% at fault for the collision. I doubt that your aging Crown Victoria has a black box, but my little Scion does, and the data from it would certainly have shown, by a simple calculation, just how fast you were going, and you would have lost your license.
the new driver you didn't manage to scare into never driving again.