The word "standardness" implies that someone is setting a standard that should be followed by all nodes; but it is known that different relay nodes are using different arbitrary criteria to censor transactions and blocks.
Again - a total misunderstanding of the terminology and how Bitcoin works.
If you are seriously at all interested in what Standard and Valid transactions are then you should read the code
I don't plan to read the code, and I should not have to. The payment system of the world cannot be defined by a (messy) program. Bitcoin should be an implementation-independent protocol, like SMTP and HTML. Anyone with sufficient knowledge of algorithms and networking should be able to understand how it works
without reading the code.
And there should not be "the" code, since the maintainers of that code would be a central authority.
Whatever "standard" means, you cannot assume that miners will not create non-standard blocks that are accepted as valid by other miners and clients. You cannot assume that every miner will run unmodified Core software; and you cannot assume that non-mining relay nodes will do anything specific.
Indeed I have little love for the current Core devs, for a dozen separate reasons. To stay on the technical ones, they include (1) claim that soft forks are safer than hard forks, (2) the "fee market" and its paraphernalia, (3) SegWit, (4) reliance and encouragement of non-mining relays, (5) modifying bitcoin as if the Lightning Network is a certain thing. Not me, but some very competent people (who also
have read the code) have objectively pointed out the faults in those items; but their criticisms have never been answered.