"Please will somebody explain why a school child should not automatically make up any work that they have missed for whatever reason? (Setting aside the cost of ingredients thing for the time being). What exactly is the big deal here?"
You don't have to do the other lessons in real time. If you have 6 or 7 hours' lessons a day you could spend a week, including weekends, making those up at an hour an evening, on top of your actual homework, piano practice, etc. That would be tiresome. Non-practical subjects do not require this. They require you to read / copy up the chapter or the notes or the hand outs, assimilate the knowledge that brings you up to speed with the rest of the class, and prove it by doing the normal homework that was set. Copying up notes or reading the handout will not take nearly as long as a real life lesson. REal classes starting with "does anyone remember what we talked about last week in terms of postive and negative ions?" - faffing about like that, settling the class, tuning them in, dealing with cheekiness, chivvying some of them up to speed, testing their understanding as you go, etc. As an individual, you just read it in 10 minutes and then you know it.
"But every piece of homework set does this, surely?"
a. yes, some say too much too young, but more importantly,
b. Yes, but this is not homework. The OP is not complaining that her dd has to all the homework set the week she was ill. She is complaining that she has to replicate the actual lesson at home, in her own time.
To me this is bizarre, it is as if I missed a meeting at work through being ill at which I was given action points in absentia. And then finding that not only do I now have to do the action points (fair enough, obviously) but I have to do a weird mime of the exact interplay of the meeting, in real time, on my own, at home, in my own time.
"Politically, I think eroding parental responsibility and extending state intervention and control in ordinary families lives has no benefit and many many negatives. "
I completely agree with this. My whole family is strapped for time, my girls are small so they are exhausted by 7 and in bed by 8 and I don't have that much time to spend with them. Every minute is budgeted and within that budget I would definitely include sensible educational stuff that supports what they are doing at school, but I resent having to allow more time for stupid nonsense. AT this point someone will pipe up, "who decides what is stupid nonsense?" and I think I can. I am an adult with a great education and great job, and I know my children better than anyone, so yes, I do think I get to decide thank you very much.
EG:
My daughter reads her stupid books from the school once a week, on the day she gets them, in 4 minutes flat to get the blasted things out of the way (I do not talk contemptuously about them in front of her, obviously) and then I write in the book that she has done it.
The rest of the week she is very keen to read, alone and to me, every single day, the good books that we choose together that are interesting and have stories, and I make no attempt to steer her towards the stupid books from school. This means that her reading diary has only one entry a week and I don't care. I believe I know best in choosing to support her reading in that way: whatever schema informs the school books, she is getting what she needs out of it by reading the goddamned things once: what I think reading is about, which is following your interests, gaining pleasure from literature, and earning ease and facility by constant practice which will then translate into a benefit for every other subject - she gets from reading widely and freely all the time. I know the school think she should read the books they send every day. I don't care. We don't do that and I believe I know best, because more than anything, I want her to enjoy it and own it.
A lot of people on this thread seem to want to deny parents like me that judgement. I think that is pathetic and craven.