Ok This is what I have to say. This is probably the opinion of all Italians, especially the ones who still live there (certainly my old friends and family in Florence).
On the ZTL of Florence (some history):
The first ZTL goes back to 1978, when it replaced the old ZONA BLU (blue zone) which was introduced in Florence in 1971, but it was very small and it included only the quadrilateral section corresponding approximately to the Roman walls area defined by the orange perimeter in the picture below plus a few more streets:
In 1988 the ZTL area as we know it today was created, as it was extended to the outer circle of walls. Some areas within the outer walls were excluded, which were included only later.
The entire project was to favor tourism. Even the last restrictions of 2011, when entire streets were closed, not only to cars, but to even public buses (Oltrarno, via Tornabuoni, etc.) had the purpose to pedestrianize totally those areas for the benefit of tourists (and merchants catering to them).
All these restrictions represent severe limitations to the life of Florentines (WHO HATE THE ZTL), and actually it was one of the factors why I moved to the US. I could not take all that inconvenience anymore, such as the inability to drive anywhere (especially because the ZTL created a lot of traffic outside of it). Whenever I needed to go downtown, I had to do it on my vespa or motorbike, often under the elements, simply because I was not eligible for a permit (my house was outside the city center). If I went by bus it would take longer to do anything and if I had to take some heavy luggage it wasn't practical at all and I would rather put it on the rack of my vespa (including a rented big electric typewriter once and a piece of furniture). This is what locals in Florence (and other cities too) have to do to get around in order to please tourists:
It is also not true that fines are for tourists only. Between 1977 (my first motorcycle) and 1988 (when I moved to the US) I must have collected at least 20 violations for ZTL or bus lane incursions. There were no cameras then, so the police had to catch me in the act. Sometimes they would take my license plate number, other times they chased me (sometimes I got away when I was on the motorbike, but never tried to escape with the car). With the cameras it's even worse. Yes Florentines know where cameras are in Florence, but they get also caught by cameras in other cities. Speed cameras are everywhere. They even caught my father in his old age, when he drove so slow that he would create traffic jams.
Since 2003 Italians get 20 points with the drivers' license. When the get a violation 1 to 10 points are deducted (depending on the violation). After you are left with 0 points, the DL is suspended for a period from 2 weeks to months. Some of my friends have had their license suspended since 2003 and nobody I know in Florence has 20 points intact for more than a few months (if you don't get tickets for 2 years you go back to 20 points).