Why the display of Unicode characters for superscripted digits are not at the same height?

Why the display of Unicodes for superscripts of digits are not at the same height? This is specially noticeable if you make two digit numbers out of the superscript digits. Some of them look fine but the rest look out of the place with respect to each other. Am I missing something? Or is this how it is?

Like jrturton mentions, ¹, ² and ³ were from a legacy character set (Latin 1) and therefore included in a different place. This also means that lots of fonts don't have support for more superscript numbers, as many only strive for Latin, Greek and Cyrillic with a few punctuation symbols thrown in. So the remaining ones are taken from a different font over which you as an author have little to no control.

As an example:

Those are the superscript numerals from 1 to 9 and 0. The run of text was formatted in Arial in Word. You see what happened to the rest of them. Contrary to what jrturton believes, there is no reshaping of existing glyphs involved. This is just font substitution.