Taxi or Transfer .. Confused by inside the walls vs outside.

Have read plenty about the fixed taxi fee from FCO to inside the city walls.

But just reading on romevacationtips about "‘Welcome Pickups’ is a new service that charges just €4 more than a taxi," .. But when I fill in my details it's quoting me 81eur .. So alot more than just 4 euro more.

However we're not going as far as inside the city walls, we're outside at Primavalle, Parco Pineto, west of the Vatican.

So does this come with a much higher price, even though it's 4 km less than the termini for example?