Why is it that C++ package managers are unnecessarily hard? – or are they?

The example provided is insufficient to state c++ package managers are easy.

Firstly the meson.build file has a few libs mentioned 1)fmt and 2)sdl2. Let's go with that. Usually all libs have version tags associated: https://github.com/fmtlib/fmt/releases/tag/9.1.0 https://github.com/libsdl-org/SDL/releases/tag/release-2.24....

Rust Cargo.toml files help you to specify the version number or place * for the latest version. It is well documented it fetches the crate from crates.io or it will specify elsewhere explicitly. I see nothing of that within meson.build in your example.

meson.build documentation states you may specify a version, but there is nothing there stating by default it gets the latest version. https://mesonbuild.com/Reference-manual_functions.html#depen... I see nothing mentioning the latest version of each package is fetched within meson.build in your example.

Next you mentioned a number of steps to follow to deliver a C++ binary: mkdir subprojects meson wrap install fmt meson wrap install sdl2 meson build ninja -C build build\deptest

For Rust, that would be one line to build: cargo build --release one line to test: cargo test --release

I wouldn't say C++ package managers are hard, but they are certainly not as eloquent as Rust.