Low level? Really? Can you point something that is achieved on axios with few lines of code that fetch couldn't do it with few lines of code too? I can't considerate fecth.get().then(res => res.json().then(data => /.../)) A Low level thing.
I don't use axios often, but if I need to intercept requests, or set global headers I always need to wrap my fetch function and creating my own "axios". Axios can do these things without hassle.
Even if some difference actually matters (e.g. setting a timeout), it would be wise to wrap axios or fetch in a custom function, which obviates the need to use either for most developers using the codebase.