LOL, Roberto!
But what he says is true: the locals are unhappy with a spruced-up Express train that doesn't have enough runs to coordinate with daily work commutes. Taxpayer $$ are essentially subsidizing a more comfortable, more expensive train that largely benefits only the tourists and is losing money while they're left to manage with the bare-bones Circumvesuviana. They're entitled to be a little cranky about that.
If you've taken commuter rail transport in any number of urban cities, you will understand the Circ. trains. They're sort of like the "L" in Chicago, the Tube in London, the Metro in Paris, the subway in New York, etc. They have zero for frills but get the job done and move many, many people every day. They can be standing-room only, have some interesting passengers, and you need to watch your valuables on them just as you should on ANY urban transport in Italian or other European, or even American, cities.
It comes down to how quickly you want to get from Naples to Sorrento, what sort of comfort you want to do that in, and/or what you're willing pay to do it.
Most expensive, comfortable door-to-door service ? Private driver.
Reasonably cheap and comfortable but with risk of long waits for one of only 4 trains per day? Campania Express. You may also have to use an additional form of transport if your accommodation isn't (what you'd consider) walking distance from the train station.
Most inexpensive, least comfortable but the most frequent trains? Circumvesuviana. The same potential need for additional transport from train station to hotel applies.
What station should I depart the high speed train in order to get on
the Campania Express to Sorrento?
You want Napoli Garibaldi station for the Campania Express or the Circumvesuviana. It's connected to Napoli Centrale so follow the signs inside the station.