I think the problem is basically because the build system has to be implemented using some ecosystem, and no other ecosystem wants to depend on that one.

If your "one build system to rule them all" was built in, say, Ruby, the Python ecosystem won't want to use it. No Python evangelist wants to tell users that step 1 of getting up and running with Python is "Install Ruby".

So you tend to get a lot of wheel reinvention across ecosystems.

I don't necessarily think it's a bad thing. Yes, it's a lot of redundant work. But it's also an opportunity to shed historical baggage and learn from previous mistakes. Compare, for example, how beloved Rust's cargo ecosystem is compared the ongoing mess that is package management in Python.

A fresh start can be valuable, and not having a monoculture can be helpful for rapid evolution.