Rust’s C FFI gives us access to decades of useful software, but the bargain is backwards. We use Rust to prove memory safety at compile time. Then we cross an unsafe boundary and trust the C library to respect a contract that neither language can enforce. The legacy code remains the cheap path, while rewriting it is the expensive one. Fil-C offers a more interesting bargain. It recompiles C and C++ with capabilities, runtime checks, and a concurrent garbage collector. Memory-safety violations panic instead of becoming exploits. Existing software often needs few or no source changes, but it pays for safety at runtime.