Which is fine until someone changes the C++ struct definition. This 'non-local' change affects the semantics of your code. Lisp's CAR definition is unaffected by non-local changes.

You can think in any language but as noted by Wittgenstein “the limits of my language mean the limits of my world." For example, while it is technically possible in any language, the ability to write self-modifying code is unlikely to be thought of in most languages. Try writing non-object oriented code in Java.