Today, if you drive 55 MPH on that expressway you will almost literally be run over; the traffic flows at 70 MPH even in rush hour.
Having FSD stick to the "speed limit" would make a Tesla un-driveable and ultimately very unsafe. Just my $.02.
You're describing a normal day in Italy, not an exception.
Limit on highways is 130km/h, it's quite common keeping 140km/h, even when there are speed controls, due to tolerance.
Otherwise whatever goes. Used to drive 150km/h pre-Vision, and 160km/h on the BMW (manual really anything above that).
If you keep 130 or even 140 you'll get run over on the right, flashed at, etc.
Expressway around the city previously had the same speed limits as the highways (130km/h), was lowered to 90km/h two decades ago. Nobody keeps 90, it goes as far at it can go.
Same on the Genoa coast, the limit is lower, between 90 and 100 due to difficult corners, I keep 130-140 safely, if the traffic allows it.
However, that's me, the human. If everyone did the right thing (impossible unless everyone goes FSD), I'm not sure I wouldn't want the car to exceed limits.
I understand there might be roads with speed limits that aren't updated, but also speed controls wouldn't be. I understand the case-by-case approach as well, but I hoped FSD could bring us down a notch, not the other way round.