Line 1 was extended to Centro Direzionale in April 2025 and the line ends there: the Capodichino airport station is under construction and expected to open between late 2026 and early 2027. Plenty of guides already sell a 'metro to the airport' that does not exist.
Naples runs predetermined fares that already include every supplement, day or night: €21 to Napoli Centrale or the historic centre, €24 to the port. A driver who puts the meter on for a fixed-fare destination, or adds a night, holiday or luggage supplement on top, is overcharging.
The airport's own guidance is that vehicles waiting outside the marked area may be driven by someone without a regular licence and can charge more than the Comune di Napoli tariff. The official rank is directly in front of arrivals; the collective taxis wait in the 'Pick-up' area about 100 m away.
Alibus is a premium line: the €5 ticket is its own product, and the Napoli Artecard (€27 for three days) explicitly excludes it. An ordinary €1.50 ANM metro ticket or an UnicoCampania urban ticket will not get you on the airport bus.
The last bus leaves the airport at 00:00 and the first is at 05:30. Between those hours a taxi is the only way in — and the €21 fixed fare to Napoli Centrale still applies at 3am, so there is no reason to pay more.