Why 01, 02, 03, 04 and not 1, 2, 3, 4?

It seems designers like to add zero to number sequences, like here:

As I understand it, from design perspective, it’s more boxy and comfortable to work with, but from user perspective isn’t it better just to have plain 1, 2, 3, 4?

Is there some history? Who was first to add zero? Is there any other initiative to do it?