You badly overestimate the technical chops of the parent-guardian cohort and underestimate the practicality of a printable PDF with key dates.
We can have both.
Any organization in 2024 creating a calendar that impacts 500-1000 people should have the awareness that people use digital calendars / apps too.
They should make an effort to publish both PDF and ical.
Since that has yet to catch on in many places -- including the HR departments of large enterprises that publish holiday calendars and the like -- these alternatives ideas are explored.
Once we have the right tools ...
It just takes one tech-savvy parent to do this 10 minute exercise and publish an online calendar that other busy parents can subscribe to.
I do find that most of these do provide some method of getting a calendar link but we’re not quite to 100% yet.