I’d love to take farmland and build cycle tracks, but realistically they are not going to be used more than a couple of times a day.
Now if you’re talking in towns and cities, sure, but be careful when using the word “every”
You say "it's impossible because X", but what is usually the issue is that cars just take over all the space and make public transport, walking and cycling impossible. I could live in the country side without a car thanks to the pandemic, I do understand that most people make choices in their life that make that harder, but those are choices made by people and infrastructure planners. They are not fixed truths.
There is so much to disect here and I do not think we can reach a common conclusion because everything is a special case. For reference I lived 9 km to the primary school, bus and store, 60 km to the nearest hospital and train station, 4 km to the nearest daily bus. I understand that it might feel strange to build bicycle infrastructure in such an environment. Luckily for us it was perfectly possible to live there and have my children ride their bicycles to school, but this was only possible because a lot of people alreadt walked on these roads, and it was quickly known in the community that my children rode there in the mornings, even if they were the only ones doing it.
Yes you need to change the infrastructure even in the country side to enable walking and cyclists, it does NOT have to be 10km of cycle track, but it might have to be that.
Banning vehicles from that lane wouldn’t work. You can’t make it one way, it already can only pass traffic in one direction at a time.
The question was
why can't every child cycle to school on a car free path way?
The answer you admit is that in some parts of the country there just isn’t the road ways to convert. You also point out quite correctly it’s often not necessary, but you still take umbridge with these facts.
The easy path is to continue scaring kids away from roads making them a barrier rather than something for transport.
So? If it’s a road that leads to a school it should have a separate way for bikes.