> they serve the same functional goal — input numbers
Well, yes and no. Same as how, when it comes to data types, it often has to be pointed out to inexperienced developers that a phone "number" isn't a number in the mathematical sense - you can't add or multiply 2 of them together to get anything meaningful. It's an identifying string, that happens to use only digit characters. "123" in a telephone number is three individual unrelated digits, whereas "123" in a calculator represents the number one hundred and twenty-three.
So the functional goal isn't exactly the same. One is entering individual characters, but on the other you're more likely to be thinking "one hundred and twenty-three" as you type its digits.
It may or may not be related to the actual reason for the inversion of layout, but the subtle difference felt like a (possibly minor) error in the initial premise.