I found this thread by Googling for a very similar situation.
Same original charge, same "amended" charge, same Santa Clara County, same year and I would not be surprised if it was the same officer...
I was flabbergasted to find out that citations can be changed willy-nilly like that. It just felt profoundly wrong to be cited for one thing, then go to court and have to answer an entirely different charge. I went to court because CVC 23123(a) has been struck down by the California Appeals Court in the Spriggs case. The Appeals Court found that there is no reason under law that drivers cannot use maps on their smartphones. I felt the ticket should never have been issued.
The "distracted driving" argument is a red herring. If an officer believes the driver was indeed driving distracted (on a real evidence - not on a spurious reasoning that "if you hold anything in your hand you are distracted") - there is no reason to not write the ticket for that on the spot. The officer clearly did not want to defend the original charge (which was clearly the intended reason for the citation) and changed the charge to something that cannot be proven or disproved by facts - and is based entirely on his judgement. If such conduct were to be permissible that would give the police literally unlimited latitude to issue baseless citations and this should not fly under our system of constitutional government.
Now, in my case I just took the "traffic school option" simply to avoid risking a point and insurance rate hike trying to defend myself against a charge that can be made solely on officer's judgement and not on any verifiable facts. However, I strongly feel the justice and due process have been denied to me and I was pressured into pleading guilty for the offense I have not committed. Regardless as to whether I would be able to get my fine money back, I intend to pursue this as a matter of civil rights and policing practices - by filing formal complaint(s).
ileventh - please message via this forum (your messaging is not enabled, so I cannot contact you) to consider if we could co-ordinate. Clearly, there is a pattern in Santa Clara County of trying to sidestep the issue of invalidated handheld phone prohibitions by re-classifying the tickets retroactively. Let's do our part to keep the law enforcement honest.

