I didn't say it was a solved problem - it isn't! - but rather that I find python's solution particularly bad. The situation in C (and C++) is indeed even worse, I just haven't been doing that for the last decade. Things I've used in the last decade that all work better, in my opinion: Bundler, NPM, Maven, Cargo, and even Go's packaging.
I always liked python, but I didn't use it at all really for a very long time until recently, and I've just honestly been surprised by the poor state its packaging seems to be in.