A lot of packages use curl to fetch their dependencies. For example with the default cross images I can't compile exonum_libsodium-sys due to error:

thread 'main' panicked at 'Failed to run curl command: No such file or directory (os error 2)', /cargo/registry/src/github.com-1ecc6299db9ec823/exonum_libsodium-sys-0.0.23/build.rs:88:17