You still use it only once
per project in normal workflows. And if you need to go beyond that, you'd have the same problem with Rust, at a minimum; it can't read your mind and install into the correct venv. It only seems to be doing that because it made one and assumes it will use that one.
If you like the per-project venv workflow, and like having it in a specific place (whether that's relative to the project root, or a parallel named venv in `~/.local` somewhere, or anything else), you can set that up as part of your project initialization, too.
Going back to your first comment:
> because of constant friction: pip, pyenv, poetry, pyproject.toml, rye - wtf?
This complaint makes little sense because it mixes and matches things from different categories. `pyproject.toml` isn't even a tool, but a config file that several other tools will rely on - including uv. Poetry and Rye are specifically trying to do the same thing uv is - in fact, Rye is uv's predecessor. Pyenv is for making separate installations of Python - it works alongside venvs, not as an alternative. Pip is just an installer; it's not meant to be compared to full project workflow tools or even to just "package managers".
Expecting one tool to work for everyone is a mistake because of the sheer variety of use cases out there. At the very least, people who only want to install Python applications and libraries are very different from those who seek to distribute their own work. (People in the first group might not even write Python code!)