Blows my mind how you guys confidently state this with authority as if that's the normal behavior, when the reality is that it probably should be - but isn't actually.
The focus on speed limit as some truth is not the best way to think about it.
It might be 15/20/25 (varies, but those are the most common values I've seen).
But in terms of what is safe, it varies far more.
There will be circumstances where driving double that limit is 100% safe in front of the school. (For example, small numbers of high-school kids standing around but far from the street, so even if they did a mad dash to the street (which that age kids will not do), they still couldn't get in a spot to be hit by the car.)
And there will be circumstances where even a one-tenth of that speed will be far too dangerous to consider. (For example, high density of elementary school kids on a narrow sidewalk with many visual obstructions.)
I have a hard time believing that you, or anyone, would drive the same speed in both scenarios without any consideration to the circumstances of the moment.
I know I most certainly would never. If there is obviously zero chance of an accident I'll drive the limit or above. If there are tons of tiny kids in brownian motion, I'll slow down to a crawl or even stop if I sense risk (like a kid disappearing behind a parked car and now I don't know where they'll pop up).
Around a school understanding the environment is way much more than understanding just the speed limits and lane boundaries.
Indeed. Sure the car knows the limit, it knows it is a school zone, it can precisely track people within the reach of its sensors (but not behind blockages it can't see through).
But it is missing the human understanding of the situation. Does it know that tiny humans behave far more erratically then the big ones? Obvious to us humans, but does the car take that into account? Does it consider that in such a situation, it is likely that a kid that its sensors can't possibly detect has a high probability to suddenly dart out from behind an obstacle? Again obvious to us humans because we understand kids, but does the car know?