Flippin heck, OP, I think you need to cut schools some slack. Some schools are really struggling, they can't even get cover at the moment if staff are off sick or having an operation or something as the agencies just don't have anyone available. So any "free" time teachers have they are having to step in and cover lessons.
I've been working as admin in a primary school for a few months and have had my eyes opened, I can tell you. I thought secondary teachers worked hard... (I've just switched over). Teachers are often in from 7/7.30 in the morning, they stay till 5.30 till they are thrown out by the caretaker, having curriculum/year group planning meetings or ringing parents about pastoral issues (some of which I would never have dreamed of bothering my child's school about, they are so trivial). As soon as they've eaten some food at home they're back prepping for next day again, up till midnight. It's bloody hard for them. They have families too eg their own children off sick or parent with dementia etc.
They are all exhausted and have nothing left to give. Must be so demoralising to come on here and read of parents who moan they've had 30 days at home with their own children (who presumably have only been off for the 10 or 11 days each) and they haven't used their own intiative to look at the plethora of resources available for free online, or suggested to their older child to ask their classmate to send a photo of their classwork to them. A GCSE/A-level student has no excuse not to do work, there is so much out there online, past exam papers, loads of stuff on English set texts, plus paper revision guides etc. Stop expecting them to be spoon fed by their teachers constantly, maybe?
With your younger child, if there is nothing regularly provided online for isolating children, have you tried phoning the school and asking for a 2 minute phone call at the end of the day with the class teacher, for an update on what the class has been doing that week so you could at least do some work at home with your child on particular topics? Maybe thank your child's teacher for all their hard work, and that you know how stressful teaching has been these past 18 months and that you appreciate everything they're doing? As I said, I'm only admin, but I have eyes, and see the pressure that schools and agencies that work with schools are under. It's become almost unbearable.
Remember also that some schools seem to be better funded than others. Some have a higher proportion of kids with additional needs, behavioural problems or social problems. Some have to share TAs between classes. Some have children who have lost parents to COVID. Teachers would rather they give those kids additional help and support, I'm sure.