The international patent framework

I have family who live outside the US, and was curious how their patent system compares to ours. Most countries in the world are parties to the Patent Cooperation Treaty (PCT) and many are also parties to the Patent Law Treaty (PLT).

As I understand it, these international treaties make it easier to file for patents in different countries by formalizing initial steps, like searching for prior art and the application format. They do not lead to an international patent grant --one must still follow through with each nation for a patent grant. They also do not standardize the requirements for patents that we learn about from our US context, including novelty, non-obviousness, utility, and enablement.

This is a little confusing at first, because the World Intellectual Property Organization (WIPO), a UN agency, refers to the Patent Cooperation Treaty as "the International Patent System", when there is in fact no such thing as an international patent:

A patent is awarded by the government of a country and is valid only within its territorial boundaries. To obtain a patent that is valid in a particular country, a request must be made in that country's patent office.

Given the complexity of interpretations on ideas like obviousness and software patents, the difficulty of reconciling these differences between countries becomes more clear. For example, Supreme Court cases have established case law for the patent system in the US, like KSR v. Teleflex did for obviousness and "person having ordinary skill in the art". I assume other nations have their own legal codes and legal doctrine, which would make it impossible to standardize an idea like enablement or obviousness without rewriting legal codes and possible invalidating existing patents in a country.