Uber service like you are used in America, whereby a regular guy comes and picks you up with his own car is illegal in Italy as courts decided in 2015 that type of service can only be provided by licensed and registered taxicabs and limo service.
Uber is therefore available only with the Uber Black and Uber Van service, whereby they summon a regularly licensed Black Limo car or van to come to you. It’s a service that is more expensive than regular taxicabs.
You can summon taxicabs with ItTaxi cab, at no extra fee, since that app is owned by the Italian Radio Taxi association.
You can also use the FreeNow app to summon regular taxicabs, but unlike ItTaxi, there is a fee of 3€ per ride paid to FreeNow.
Since 2022 Uber has a Joint Operating Agreement with ItTaxi, therefore you can summon a regular taxi also using your Uber App. However, like with Free Now, there will be an extra fee of 3€ going to Uber on top of the price of the ride.
So the cheapest option is to use ItTaxi or even better to walk to a Taxi stand, because when you summon a taxi via app or phone call, the meter starts from the moment the taxi is called and comes to you, whereas if you pick the taxi at the stand, the meter starts when you get inside the taxicab and the taxi starts rolling.
Do not hail taxicabs from the curb, they don’t stop. When a taxi is traveling it is either going to pick up someone or has already a customer on board. In all other circumstances, the taxi cabs stay parked at taxi stands. Gasoline is too expensive in Italy for taxi drivers to go around hoping to be hailed.