I don't fly in and out of there. It is mostly the low cost carriers, but I have to admit I've heard from others that taxis at Ciampino sometimes try to jack up the prices. Evidently, they feel that the 30 euros is way too low. It would cost about 30 euros to just get to the Aurelian walls by meter, much less drive around within them up and down one way streets, stuck in traffic in the city center. Although FCO is further away, they are both 30-40 minutes into the city center. The comune should probably do something about that, but I wouldn't hold my breath.

If you have reasonable confidence in Italy and you are going within the walls, you can just get out and give the 30 euros when you get to the destination. If they give you grief, the taxi's registration number is on the side of the outside door, along with the phone number to where to report them. I'm not sure it's worth the hassle for someone not used to arguing in Italian if it's just a couple of euros.

At FCO there's a lot of international flights, including people from the USA who tip. I suspect at Ciampino where it is mostly low cost intra-European where tipping is not expected, and 30 euros is all they're going to get for waiting for a fare for hours, this is their way of making up for it.

By the way KLouis, "fuori le mura," that's pretty impressive. Italian has tons of grammatical rules and exceptions. Le mura is one of the rare exceptions that you pretty much have to speak like a native to not get wrong. "Wall" is like lips, arms, and other exceptions where the usual grammatical rules have to be broken, so are usually misspoken except by native speakers. "Wall" is so complicated that you have to use different rules if you are talking about a wall in your house, an wall around a city, or an imaginary wall as in, "He is so hurt that he built a wall around himself and won't let anyone get close to him anymore."