Because the aarch64-unknown-linux-musl target has only shipped the static files.
$ ls ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/aarch64-unknown-linux-musl/lib
crt1.o libpanic_abort-258f5d010b656084.rlib
crti.o libpanic_unwind-765c392663bd34b7.rlib
crtn.o libproc_macro-f89fa6bc1543b74b.rlib
liballoc-c47e11e0b4c869e2.rlib librustc_demangle-85b43da92537c77f.rlib
libbacktrace_sys-1059e0ba7f05fd67.rlib librustc_std_workspace_core-5a60e280b382f06e.rlib
libcompiler_builtins-566972fa63f867ee.rlib libstd-b806fbdf01014e64.rlib
libcore-8010f7064010be9c.rlib libterm-5a3c233fedc016bd.rlib
libgetopts-21c5ddfdf14ab53b.rlib libtest-d65243ce23c10440.rlib
liblibc-1d32a47a0bdcb0a2.rlib libunwind-f8a77019eff82b98.rlib