I didn't write that, someone else did.

According to wikipedia: the current shape and layout of the license plate was adopted in 1956, with the numbers black and the background yellow, which superseded all previous shapes and color combinations. This changed in 1963 to yellow characters on a black background. The next change was the yellow on blue in 1969. In 1980, the blue plates were discontinued in favor of the reflectorized white background with blue letters and the setting sun at the top. This was used until sometime during 1987, when the setting sun was discontinued ("too expensive"), but slight variations on the blue letters on a white reflective background has been used ever since. In 2015 the yellow on black was re-introduced for specialty plates. Horseless carriage plates are white on red, and antique motor cycles are red on white.


wikipedia lists some 30 versions of specialty plates, and the DMV will make just about any type of specialty plate, provided you can guarantee a sufficient number of orders, which is something on the order of ten thousand. Since Calif had 15.1 million registered motor vehicles in 2018, this is a mere drop in the bucket. Double checked the numbers, and Australia (all of it) has now surpassed Calif by about 4 million vehicles.