Simulcasting is attractive for scanner listeners, but has little utility for the CHP. Aside from problems keeping transmitters synchronized there is no need for all cars to hear all transmissions.
What problems synchronizing transmitters? GPS disciplined reference sources are quite affordable, and modern transmission equipment (microwave radios, multiplexers, etc.) are extremely stable.
Having been involved in engineering and maintenance of analog simulcast systems since the 1970's, I really don't understand the source of the myths that low band simulcast is difficult to get right. It's not.
Low band has plenty of other problems, but synchronizing transmitters is not one of them.
The need is simple... a large coverage area with a single common channel. It's a spectrum conservation technique.