> It is not obvious that you need to include comparative function for a straightforward numerical sort ?

No. It's not obvious.

Python -

    a = [6, -2, 2, -7]

    a.sort()

    print(a)

PHP -

    $arr = [6, -2, 2, -7];

    sort($arr);

    print_r($arr);

Rust -

    let mut vec = vec![6, -2, 2, -7];

    vec.sort();

    assert_eq!(vec, vec![-7, -2, 2, 6]);

The expected behavior is a default natural number sort.

What other default was chosen? String comparison for some value of Strings, coerced from the integers in some way.

If you have to research a bunch of implicit behavior to understand how sort works for numbers. I believe that's unintuitive by definition (simplest case is more complex than necessary). Fixable with a required flag or specialized functions (eg PHP).