I’d like to point out that it’s impossible for Rust programs to handle globs correctly themselves via env::args(). That’s because the args are already split and unquoted in the form exposed by Rust’s stdlib, and the difference between * and "*" is lost.
So even if we agree that glob expansion does not belong to stdlib and is each app’s own problem, there still has to be something in the stdlib to expose unparsed raw arguments to allow apps to implement globs themselves.