Is it the definite article?

So, to reiterate, when it comes to when to use the "the", the only universal rule is this:

Some rules (such as the two you've given) might hold 95%+ of the time, but unfortunately there may be weird and arbitrary exceptions that you'll just have to learn.

Source: https://ell.stackexchange.com/questions/365074/the-use-of-the-definite-article-with-the-names-of-museums-art-galleries-etc/365083#365083

Is it capitalization?

Because a cursory look at the Wikipedia page for capitalization also reveals that it is not without its quirks.

For example:

planets and other celestial bodies: "Jupiter", "the Crab Nebula"; and "the Earth", "the Sun", or "the Moon" should be capitalized according to the International Astronomical Union based on its manual of style, but style guides may suggest differently.[19]

Source: https://en.wikipedia.org/wiki/Capitalization_in_English

Is it the fact the way something is written almost has no bearing on how it's pronounced?

Please tell me your thoughts.