In the introduction here, it states that the ISO module standard for Prolog was a failure. Can anyone elaborate on this?
The system you cite, SWI-Prolog, is a system whose core is developed by a single developer. Such bold statements as those you quote are his very personal opinions. In the past, SWI did follow ISO standards for a certain period. Then, recently changed. If you want to read more about this, please refer to this answer.
There are systems that are conforming - in particular: SICStus Prolog sicstus-prolog and GNU Prolog gnu-prolog.
In case you want to know more about the purpose of standards, in particular ISO standards, refer to your national standardization body. They certainly offer 1- or 2-day introductory courses. SO is not a place to discuss this.