Why does `cd /../` not return an error in bash?

Question

In bash (or, I'm assuming, any linux shell), I would expect cd /../ to return an error. I interpret that to be asking for the parent of the root of the directory tree. Since it's the root of the directory tree, I was under the impression that it has no parent.

However, it returns no error, and looks to be equivalent to cd /. I would also expect an error from cd / && cd ../ for the same reason: asking for the parent of the root directory, but it has the same result.

Why is this?