The only issue here is with input devices. The Greek alphabet is standard Unicode, so it's not more expensive to render or manipulate for your text editor compared to standard latin.
To be fair, input devices are a pretty serious issue here. Probably the single most common operation I do on code is search it. If I can't type what I'm searching for easily, that's pretty annoying.
> To be fair, input devices are a pretty serious issue here
That's true. I'm currently using an emacs extension that allows me to convert to greek unicode LaTeX-like string (\alpha, \Gamma, ...), butI understand that's more of a hack rather than an actual solution.