Except, now you have one that you expect and the other you don't. This doesn't make the language anything but more inconsistent. I prefer consistency inside a language far more than familiarity between languages.
typeof x; // throws an error
let x = 1;
typeof x; // returns "undefined"
var x = 1;
let x = 0;
function typeof_wrapper(y) { return typeof y; }
(function() {
typeof_wrapper(x); // throws an error
let x = 1;
})();
(function() {
typeof_wrapper(x); // returns "undefined"
var x = 1;
})();
You're essentially arguing that a feature added because the old behaviour was undesirable is inconsistent because it's not exhibiting the old undesirable behaviour.