The problem with old Python code is that you then have to hunt for exactly the right version of the right libraries that can work together when the stars are aligned.
Isn't that true of any packaging system? (npm, RubyGems, etc) Perhaps it's a bit easier, with the respective spec files, but it's still a bit of a hunt.
No. Decent packaging systems like used in the Java world have deterministic or mostly-deterministic dependency resolution; semi-decent packaging systems like the ones you mention have lockfiles. Pre-uv Python packaging is uniquely awful.
Depends on exactly how the project is managed. Older python tooling (`pip` module) doesn't have a native mechanism to differentiate between the spec (direct dependencies) and freeze (all dependencies, including transitive).
