Taxi for 4? (2 couples)

Trouble is nobody knows all of the small local restrictions. I have not read any reports of taxis being limited --- But wait till you are on the ground. And, besides, the policy could change tomorrow.

Note that cars tend to be smaller in Europe, so it may be hard to get four people's luggage in the luggage space of the vehicle, even if Covid rules permit a passenger in the front-passenger seat. You hope the smallest cab will be a two-row hatchback, but it's hard to be sure. "Car services" have Mercedes sedans with plenty of space, but cabs not so much.

There are never enough cabs in Sorrento, so you might be routed to a minivan or larger, possibly at a higher price. I believe we were overcharged for an unmetered taxi in Sorrento. Note that Sorrento closes some streets (or did, pre-Covid) each night for the Passeggiata. You didn't ask about the Circumvesuviana train to Sorrento, but it can be so crowded that taking it with luggage is a trial. You might hire a car service from Naples if that fits your itinerary and budget.

A taxi in Venice is obviously not an option, unless you mean a water taxi.

All other cities will have taxis that can accommodate 4 passengers (generally a minivan o large vehicle). When you are at the station taxi stand specify to the attendant there are 4 of you, and you will be accommodated in the first available minivan in the taxi line.

Currently (until 31 Dec 2021) passengers cannot sit next to the driver, however we don’t know about the rules at the time of your travel.

You cannot ride a standard taxi in 4 people, because the Covid law says that the front seat cannot be used and in the back seats are allowed only 2 people if not of the same family.
4 people can be on a minivan (9 seats car), so you have to look for that kind of vehicle.

I have had many good experiences dealing with www.suntransfers.com. I have used them in both Rome and Milan and they were wonderful for me. It is simple to book online and the drivers wait for you outside of baggage claim holding up a sign with either your name or Suntransfers on it so it is very easy. Water taxis in Venice are easy to book or just walk up to on the docks a short walk from the airport but I'd recommend the Allilaguna (basically a water bus) to transfer you from the airport dock to Venice. I have never used a taxi in Florence so I am sorry to be no help there. But as far as Sorrento goes, you can't go wrong with Monetti Taxi. I got his name and contact info from the RS guidebook and he was awesome. We booked him for a day and he drove us all over the Amalfi Coast. He picked us up from our hotel and drove us from town to town filling the time with his great stories. We told Raphael Monetti, our driver, about the taxi situation we experienced in Sorrento the night before. We were hanging out very late at night and it was hard to find a taxi. When we found one to take us to our hotel is ended up being very expensive. We were needing a taxi the next day as well and Mr. Monetti agreed to take care of us.He picked us up, took us to the train station in Sorrento (for a day trip to Naples) and he picked us up that evening from the train station and returned us to our hotel for a more reasonable than our other taxi experience. I highly recommend using Monetti Taxi for the Amalfi Coast area.

Thank you Jack, those are good tips. And thank you everyone, you've confirmed what we suspected, we'll look into getting a car service arranged.

Another car service highly recommended. topexcursionsorrento.com

We used them 3 times for our trip with 4 people. Giovanni is excellent.