As a C++ developer, I maybe-ironically have this same complaint with JavaScript projects ;P. I particularly hate it when people embed minified versions of libraries, as line-based search and display then will experience a hit for essentially every query on the one giant line that is tens of kilocharacters long.
If your language lacks a de facto way to install dependencies, people will commit vendored code. See: C, C++.
If your language's package manager puts your deps within the repo directory by default, people will commit the vendored code. See: Node, Go (since go.mod).
As long as we can all agree that committing compiled code is a crime punishable by 24 hours in the shame cube.
