Harriton High, the shape of things to come?
errant.me.uk
errant.me.uk
In the US, I'm not so sure. Yep, the Harriton High mess is being ignored/suppressed by the media about as much as the "Cash for Kids" crime of the decade in the same state (two judges extorting/taking bribes from a private prison company, to whom they illegitimately sent hundreds, perhaps more than a thousand kids (create a blog critical of your teacher, go to jail! (real story))....
But we push back a lot more than the subjects of the U.K. do or can, we have much more responsive political system, things aren't such that New Labour's explicit class war against the rural part of the nation could work here, ASBOs would be held unconstitutional here, we still value privacy more, etc. etc.
At worst case, we have retained our firearms while the U.K. started stripping them from their subjects in the '20s (terrified by the Bolshevik revolution), they judicially nullified self-defense in the '50s ... I could go on and on, but the bottom line is that while this may be the shape of things to come elsewhere, I expect American Exceptionalism to continue.
No, from this side of the ocean the US seems to be treading dangerous ground. The idea that a school could interfere with home life without serious grounds (ie abuse) would be considered outrageous - though people are trying to bring it in. I mean it in the politest way but it is not national policy that is the danger here. If local policy - such as that in school - gets us used to the idea of being monitored then national policy will emerge faster...
And that's certainly not true here.
As for your latter point, the US principle of federalism, which leaves issues like this firmly in the hands of localities (think cities for a first approximation) means we have thousands of Petri dishes in which all this is going to play out.
The theory here is that a school district like this one and others may misbehave, may or may not get formally slapped down, but as long as not too many others follow its lead we're OK (you can in theory always vote with your feet, or home school etc.). And I'm pretty sure this example will help achieve the right result for most school districts.
On the other hand, there are a variety of strong and not strongly opposed programs to have schools quite explicitly interfere with home life, e.g. the "Parents As Teachers" program, which has seen a lot of abuses ... and that's a very real problem. Although I don't know how widespread, since my home state and the one I've retired to is one of the pioneers in it.
There is a general conceit (and probably not just on the Left) that if the parents aren't doing their jobs it's up to the government, often the schools, to step in. Free hot breakfast and lunch for the poor are a nationwide Federal part of that (with all the red tape that implies).