Obviously I don't object to fences being big, I object to them being impermeable. That's not just a problem for me and other humans; migtatory animals get seriously impacted by these long one-dimensional structures parcelling up the landscape as well. There have been proposals for landscaped bridges to link sides of highways to allow moose and other animals to cross, but the cost of doing that extensively is quite prohibitive.

By the way, I agree with your characterization of humans as being just like other animals. But if beavers were constructing hundred-kilometre-long barriers that blocked off our migratory routes (ie, roads and highways), and routinely shot or overran humans that attempted to cross them, then I think we'd consider beavers to be a serious problem too.

When your neighbour says she avoids putting chemicals in her food, do you cross your arms and say "even water is a chemical"? Or do you accept that her usage of the word points to a valid region in concept-space that isn't hard for you to understand, if you aren't hung op on dictionary definitions?

I wrote a cousin comment explaining why, despite the fact that humans are part of nature, there is a qualitative difference between human structures and beaver dams / coral reefs. It's not human bias, but human power and social structures that cause the difference. Or else, as I mentioned there, you're welcome to bring wire cutters with you on your hikes and treat fences the same way you treat other natural barriers.

This is also why, in a post apocalyptic movie, the decaying artifacts and skyscrapers of a lost society feel more like a natural landscape than artificial structures. It's because they lose the power structure that backs them.

Insisting on a useless definition of "natural" that encompasses literally every object in the universe just makes communication a chore.