We used to have computers in schools, on which we did all the things you present as requiring a cell phone to do, only without the persistent Internet access. Somehow we survived.
Many people are more mobile now.
And schools are increasingly supporting remote access and activities. It is especially fantastic for multi-home families where whatever a kids needs is often somewhere else.
> Somehow we survived.
This phrase is used a lot, but I seldom find it persuasive.
We survived without tools that didn't exist in large part because they didn't exist for other people too.
But when they arrive, and become popular, they change the balance of other things, whether any individual wants them to or not. Sometimes they are so popular and useful, they raise the baseline of what people need.
> would be solved with a little bit of advance planning instead
We needed more planning, because ...? I am lost as to your criteria here.
We solved many complex family issues with smart phones, which the kids used responsibly, largely due to lots of planning of healthy activities and quality use of time.
The kids also competently leveraged their phones for other valuable benefits, and it was especially nice for me to be able to contact them at any random point (outside of classes), without having to know where they were. They are my kids - being electronically present, via voice, text, pics, gaming apps, etc., when I was not able to be physically present, meant a great deal.
> Obviously your mind is made up
My "mind is made up" because ...? What is your basis here?
Throwing around an empty (potentially projecting) accusation, does not make it true.
For 25 years and going, we have adjusted our parenting roles by trying new things, seeing what works, seeing what stops working, and adjusting. "Making up our minds" would not be a useful means or goal.