I have read that it can be difficult to get taxi drivers at the Napoli airport to agree to use the fixed rates. Do you have any suggestions?
We used the Alibus which goes to the Centrale airport. Here is a recent thread:
https://community.ricksteves.com/travel-forum/transportation/napoli-centrale-to-airport
Somewhere online you can find the taxi rate sheet for Naples
Print that and show to driver
ETA
Here you go
2024 so not sure if there is an update
https://www.taxinapoli.it/wp-content/uploads/tariffario-taxi-2024-eng.pdf
My hotel, Starhotels Terminus, was across the street from the Central Train station so taking Alibus for 5 euros was a no brainer. If your hotel has a similar location, consider Alibus.
Last September we went to the main taxi stand with the rate sheet in hand. The driver at the head of the line tried to talk us into a higher price. I refused. He pointed to another taxi who took us at the published fare. The push back from him was firm, but not confrontational.
I was in Naples recently and had various experiences with Naples airport taxis. We had to take a few taxis to and from the airport to retrieve missing bags.
On arrival in Naples we knew the taxi should cost about 25 euros to the city, however we paid 36eur because we were too tired to argue.
The following day our Airbnb owner booked a taxi for us to return to the airport for our bags. It cost 21 Euro. To get back the city we refused to pay more than 25 euros (the recommend rate), and requested the pre-set flat rate before getting into the taxi. Some drivers refused to take us unless paid more, others were happy to oblige.