I really think this deserves its own thread  

For EMS operators it's different. On a call we pretty much always fall under a form of local ordinances that allow us to land with out permission. in California, non-emergent operations INVO a school require prior approval from DOT. Again, for EMS we are given a ton of leeway.

The OP was a private operator picking his son up from school. I would not have trusted the principal to handle all local communication. I certainly would have reached out to school security myself. That said, I likely never would have done this. It always causes more problems than it's worth.