>So is your claim that, because a "standard" says something and claims it's a "specification", that is sufficient to guarantee that every implementation does exactly what the "standard" or "specification" says.
It's the other way around, a standard specifies the requirements of a conforming implementation, and then an implementation can claim conformance with respect to that standard. With C++, many well-known implementations do claim conformance to the standard such as MSVC, GCC and Clang. With Python no one makes such a claim, not even the CPython reference implementation, because there is no standard to conform to. On the contrary what you do find are implementations that try to be compatible with CPython reference implementation specifically, such as PyPy and Pyston but no one claims to conform to the Python reference manual. The reference document simply describes how some Python implementations happen to work, but it does not prescribe how a Python implementation is required to work in order to be in compliance.
If tomorrow CPython decides to add a new feature to the language, then the reference will be updated to include this change because the reference is a reflection of the implementation.
If tomorrow the C++ specification changes, then it's GCC or any compiler that claims conformance that will update to include that change because with C++ it's the implementation that is a reflection of the specification.
That's the key difference between a descriptive document and a prescriptive document. This may seem like a quibble as you put it, but quibbles can lead to multimillion dollar lawsuits as Microsoft learned in the 90s when they claimed to have an implementation of the Java specification and then were sued by Sun Microsystems because Microsoft's implementation did not in fact conform to the Java standard.
Microsoft ended up paying 20 million dollars over this so called "quibble":
https://en.wikipedia.org/wiki/Microsoft_Java_Virtual_Machine...