I actually don't think you are being unreasonable OP.
Before the pandemic it was always trotted out on Mumsnet that 'schools aren't childcare'.
I could end up lambasted for saying this, but I think most children above the age of ten or so are able to stay in themselves, so long as the parent is phoning regularly, the house is as safe as possible, and healthy no cook meals and snacks are left. Older siblings ie 13/14 are mostly perfectly capable of looking after children of around 5 and above.
For the duration of the summer holidays last year, I had no choice. Single parent, out of school shut as within school, no childminders available to cover, holiday clubs finished at 5 and I finish at 5.30, believe me I tried everything. DC aged 13 and 9. The benefits / jobcentre are not very understanding of people just quitting jobs and I can't afford the five week wait even if I wasn't sanctioned for quitting.
I called every hour, they could call me. Strict rules of no answering the door, no kettle / cooker / shower. I trust them anyway but I warned them that I'd be returning early on a few of the days just in case.
It's not ideal no, but a few decades ago was viewed as completely fine.
What about trusted friends popping by?? Family if that's an option?? If a two parent family, reducing outgoings and one parent quitting until they can manage shifts around each other??
The government should be building online learning for these kinds of eventualities.
Don't get me wrong, I do understand that it's a difficult situation for some, but the whole pandemic isn't ideal, and the virus doesn't care about our jobs or the economy, it just is what it is and we have to deal the best we can.
If schools have to close or be part time to control the spread, that's what needs to happen.