There's an edge case here or an edge case there where something didn't work as expected.
Construction zones and first responders are not an edge case, they are a well-known case. Also, stopping for school busses.
Tell me you don't know how model training works without telling me you don't know how model training works.
Autonomous vehicles (probably not including Tesla) already handle first responders correctly probably 99.99% of the time. They already handle school buses correctly probably 99.99% of the time. So what remains are, by definition, edge cases that for whatever reason require additional handling beyond the basic "Is this an emergency vehicle/school bus? If so, pull over and stop" rule.
For example, one edge case is figuring out how to clear a path for an emergency vehicle when there is no obvious place to pull over because of other cars stopped nearby. Sometimes the correct answer is to actually drive in the direction the emergency vehicle is going until you find a spot to pull over and get out of its way. This isn't intuitively obvious, and a lot of human drivers will struggle with it as well.
For another example, at least one case of Waymo vehicles illegally passing a school bus was caused by a remote operator not noticing that the vehicle had flagged the presence of a school bus and telling the car to proceed anyway. Sometimes, having a human in the loop actually ends up making things worse. :-)
what AV companies will do to prevent bad interactions with emergency vehicles will always be "exactly what we're already doing"
If you turn your brain on, you can think of other solutions. Something like, "have a safety driver."
At that point, what's the point of them being autonomous? At some point, you have to cut them loose and see what mistakes they make, because it is precisely through detecting those mistakes that you figure out what edge cases remain inadequately handled in the model. And understanding how the vehicle attempts to extricate itself from problem situations is critically important in figuring out what additional training needs to be added to prevent similar occurrences in the future.
So basically, your approach likely leads to a future where the models never learn to handle emergency vehicles, because safety drivers keep having to intervene before they can gather adequate data. That approach just doesn't work.