They can, but you need the right tooling to make sure small changes don't dramatically change your binaries.

https://dev.chromium.org/developers/design-documents/softwar...

I don't think so. Compilers may change the output binary drastically, due to optimisations and other things, despite the source changes being small and localised. I'd argue that such behaviour, while desirable when creating a new binary, is counterproductive when trying to make a "minimal diff" of an existing one to fix something and not make other unnecessary changes at the same time.

There's also this to consider: https://blog.regehr.org/archives/294