Ok, yes, but that's just the kernel, and it's cheap only relative to a full VM. A container may or may not be cheap depending on the language runtime and whatever helper apps you're bundling. Bundling the python interpreter or a Java VM into every app isn't cheap.

This reminds me of early web servers and CGI's. A CGI can be relatively cheap to run as long as you write it in C and don't link in too much; not so much for a scripting language.

Redundancy can happen at multiple layers, so deduplicating at one layer might not be enough, depending on the situation.