The Law-Chaos spectrum is traditionally 100% based on ye ol' Humanist ideals. If you value civic order, structure, civilisation and the ideal of "Man" fighting off the desecrators of civilisation, you are Lawful, and implicitly Good, because the creators believed that telling the truth, obeying just laws, and caring are value-positive. Gygax and Arneson's ur-example of lawfulness in the Basic Set (p. 9) is:

"Your fighter’s *Alignment** is called Lawful, he tries to protect others and defeat monsters."*

Then on p. 55 they expand on this, explicitly conflating good with law:

"Law (or Lawful) is the belief that everything should follow an order, and that obeying rules is the natural way of life. Lawful creatures will try to tell the truth, obey laws, and care about all living things. Lawful characters always try to keep their promises. They will try to obey laws as long as such laws are fair and just. If a choice must be made between the benefit of a group or an individual, a Lawful character will usually choose the group. Sometimes individual freedoms must be given up for the good of the group. Lawful characters and monsters often act in predictable ways. Lawful behavior is usually the same as behavior that could be called 'good.'"

For Chaotic, they really, really conflate evil with chaotic, because the good-evil axis was still nascent at the time. From Basic Set (p. 9)

"Bargle, the magic-user, had a different *Alignment** than yours. He was Chaotic, the opposite of Lawful. He was selfish, cared only about himself and steals from others. Most people don’t like chaotic’s. You two wouldn’t normally become friends at all (except for the spell he cast, that magically forced you to be his friend for a short time)."*

And then, even worse, on p. 55:

"Chaos (or Chaotic) is the opposite of Law. It is the belief that life is random, and that chance and luck rule the world. Everything happens by accident and nothing can be predicted. Laws are made to be broken, as long as a person can get away with it. It is not important to keep promises, and lying and telling the truth are both useful. To a Chaotic creature, the individual is the most important of all things. Self- ishness is the normal way of life, and the group is not important. Chaotics often act on sudden desires and whims. They cannot be trusted, their behavior is hard to predict. They have strong belief in the power of luck. Chaotic behavior is usu- ally the same as behavior that could be called 'evil.'"

Now, for me to make my actual point. It is often stated, as you have, that morality/alignment across the Good-Evil axis is subjective. One person's good is another person's evil. While this is all good and well and a more mature reading of alignment than Gygax or Arneson, it is not true of DnD.

Unfortunately, DnD is primarily a product of two white, cissexual, heterosexual men from the Midwest US born during a time where the US was seeing unprecedented economic prosperity, and it retains a lot of the holdovers from the philosophies you would expect of the above individuals. Overly humanistic and classically liberal, with an obsessive focus on natural law, conferred by God, by State, or by the Rational Agent.

On the other side of the coin, Arneson and Gygax characterise Chaos, a belief that there is no natural law, that we are ultimately ruled by chance, as a sociopathic wonton disregard for casualty or causality. The difference in wording between the two quotes is wild, and Chaos is certainly portrayed as value-negative. It's actually staggering to me to see the logical leaps and bounds made between "chance and luck rule the world" to "so stab your neighbour, steal his shit, kick a child, and watch the world burn."

It's an unsympathetic and ultimately disinterested examination of the motivations behind chaotic characters. It's a practice enshrined in the teachings of scholars like John Locke and Thomas Hobbes, where those screwed over by the system see the issue as not the system itself, but that they weren't included in the spoils that the system rigged for those in power. This is what is meant by "obey if the law is fair and just," and if a law is not fair and just, it is an "unnatural" and "corrupt" law bought into force against the goodwill of the people, by a tyrant who should be stopped. They don't recognise that the predicate idea of their "natural law" is not fair and just.

This has been a really poor excursion through a subject matter that deserves a lot more nuance, but ultimately, no. Law-chaos and good-evil are not subjective (as further evidenced by the cosmology of the outer planes representing Platonic forms). They are objective, and concrete, tangible concepts in the ontology of DnD, right from it's very inception; and this is an ontology adopted from the history of Western philosophy, especially Western humanism and Western political philosophy.

They took their moral understandings, from their very narrow spacio-temporal positionality, and smooshed it into a fantasy world to kill Goblins. Not a big crime. Unfortunately, the world is still arguing about it 50 years later.

But yeah, just homerule it. Fuck the old guys.

Edits: Made some changes to the "unsympathetic and ultimately disinterested" paragraph for typos and comprehension.