Well, for once Rust's type system can enforce the usage of objects (e.g. temporary file must be used or deleted).
>> How is a 100 lines of rust easier to maintain than 10 lines of shell script?
In 10 lines of _proper_ bash you won't be able to even check if the arguments supplied to the script even exist, let alone parse something more than simply subscripting argv[].
How is a 100 lines of rust easier to maintain than 10 lines of shell script?
It's exactly what the other commnet said: "Writing a shell script in rust would be obnoxiously difficult for no real benefit."