Julia's package manager (for one) works great and can manage non Julia packages. the problem with python's system is that rejecting semver makes writing a package manager basically impossible since there is no way to automatically resolve packages.
Could you clarify what you mean? pip and every other Python package installer is absolutely doing automatic package resolution, and the standard (PEP 440) dependency operators include a compatible version operator (~=) that's predicated on SemVer-style version behavior.
