Why isn't UTF-8 the default encoding for GitHub?
Does that mean that there are any drawbacks to change from the default "cp1252"?
Does it have anything to do with using GitHub across platforms between Windows and Mac OSX?
The question is asked from using GitHub, but can be asked about Git in general.
I'm mostly doing development in .NET, HTML5 and Javascript, if that matters in the subject.
Wild guess: are you using TortoiseGit? Is that were you're seeing a default encoding set to cp1252?
If so, it's simply TortoiseGit using the default encoding of your Windows installation.
Edit: Exactly the same is true for the Git GUI
Here's a discussion from a git developer's mailing list giving an explanation: