I was being flippant but... things actually line up if you force everything to tabs too (or “smart tabs” if you really really want alignment for some reason).
Except with tabs everyone gets whatever width they want. Tab width is configurable system wide (and even in GitHub’s terrible web view).
Spaces are objectively worse in every possible way and require workarounds and editor hacks to make them behave like tabs. Skip a step & just use tabs: much better.
Note that the use of tabs has caused un-alignment. You've claimed that tab width is configurable in git's web view, but I can't figure out how to do it.
And further, if it requires me to configure in a certain way, then it's not really true that "everyone can configure tabs how they want".
Spaces. Set it and forget it. Works everywhere, every time. Objectively better.
You can't really say that definitively without ignoring the laundry list of negatives that come with spaces. Spaces are not configurable at all. That, in itself, is reason enough that Tabs are "objectively better".