Long before open source was a thing, and repos were even thought of -- I always had a few 1,000+ line personal projects I could dig up and show people.
right, and plenty people don't have large personal projects, or not personal projects that align with their work skillset, and the question is extremely vague what scope you're looking for.
It doesn't have to be a public repo of course. They can just send zip file.
You need an equal comparison across all candidates.
"We'd like to see a code sample -- something we can build and compile, that you feel is representative of your skill level."
Sounds pretty straightforward and egalitarian to me.