1. PADI certification requires the instructor to teach to its minimum standards (minimum from the sense of no more than these).
All agencies require their instructors to teach to their standards. PADI does not require that instructors teach more than is in their standards. Still, in every PADI course I have ever taken discussion and information has extended far beyond what is in the PADI materials, and in each I've received supplemental materials from my instructors.
The agency does not encourage the instructor to teach anything beyond these minimum standards.
You are correct. The agency does not encourage instructors to teach additional material not in their standards. They do not, however, prohibit it.
Within the standards, they are told to teach those standards and skills to mastery level. Something that may well not be happening as well as it should -- a failure I place on the dive shop owners and profit motives rather than on instructors.
BTW, your insistence on using the term "minimum" continually shows that you are not merely interested in discussing factual observations. In education, as has been pointed out to you in this thread and other places, standards are. Using the adjective "minimum" is simply grammatically unnecessary, unless of course what you're trying to do is making a value judgment to take a swipe at standards you don't like. Which does point to bashing rather than having an discussion about observed differences.
It is possible to inform people about differences in philosophy and content without being judgmental when doing it. If your goal is education and not proselytizion then discuss the differences.
The instructor may not test on anything beyond the minimums and the minimums are the only criteria for certification. Once met, the student must be certified.
While it is true that one must only evaluate a student based on mastery of the specific skills, there is nothing in the standards that limit how many times those skills may be drilled (there are minimums but no maximums), nor is there any requirement that those skills not be evaluated using proper trim in the water column rather than on the pool bottom. And what constitutes mastery is defined in the OW standards as:
During the Confined Water Dives,
mastery is defined as performing
the skill so it meets the stated
performance requirements in a
reasonably comfortable, fluid,
repeatable manner as would be
expected of an Open Water Diver.
There is plenty of leeway for an instructor to have very high standards with respect to what passing a skill entails.
What the instructor may not do is use a different standard of mastery among different students, nor test other skills as part of passing the course.
But not having to test other skills does not mean that the instructors can not present them, have the students practice them, and even hold off moving onto required skills until the instructor is happy that the students are comfortable in the water.
There are 5 required confined water dives, but there is no maximum time frame for each dive. I don't believe it would be against standards to run each dive according to how long the instructor's air lasts, and if a student or 5 need to change their tanks, so be it.
Advantage: The training course is universal. The same course is presented in all geographic areas worldwide. This allows precise quality control.
Disadvantage: What is required to train a diver is not the same in all locations. Any program designed for warm water omits other requirements.
This is true and is, I think, a legitimate complaint about the PADI OW course as it is frequently mis-applied. The caveat here is that PADI OW certification does limit a diver to diving in conditions similar to or better than they those in which they are trained. And I don't personally see it as a cop-out to state that some dives are simply not suited to OW trained divers as OW is envisioned under PADI's system.
PADI's approach is modular, and the OW course is envisioned as a shorter course designed to address the needs of the majority of divers -- who are warm water vacation divers.
In my local environment, by way of example, the lakes are frozen 5 months of the year. Should an OW diver be trained to dive in both thick and thin ice conditions as that is the local environment? I personally don't think that is the case.
Other agencies recognize that the instructor's knowledge of the local diving conditions is a valuable resource.
PADI recognizes this as well, and makes specific references in the standards to the instructor applying their knowledge of the local conditions to evaulate suitability of sites for OW instruction -- and thus by extension drawing the lines as to what local dives are suitable for OW trained divers and which are not.
The onus is not on the organization, rather the instructor to decide when the student should be certified. This is a distinct difference to the PADI training philosophy.
Advantage: Divers are trained to dive safely in the local environment.
Disadvantage: As local environments vary, QA is more difficult to assess. Training requirements are more extensive, which affect the profit margins of those trying to be cost-competitive with PADI shops.
Actually, just trying to be cost competitive, it has nothing to do with agency. The more subjective you make training assessment, the more a shop can be negatively impacted by instructors who are overly conservative. But a more serious issue when dealing with a larger organization is that of instructor conduct with respect to students and applying the same standards across the board even within the same course.
2. The PADI training philosophy is modular in a slightly different way to the other organizations. Using rescue as an example, this is purposely omitted from initial training requiring the diver to take advanced and rescue courses before this is taught.
Advantage: This encourages the diver to seek further training, as his knowledge is insufficient to maintain diver safety . . .
This is a matter of opinion that is not supported by objective data. We may never have this data, and while it is a rather common belief, there is no way of demonstrating that it is true or not at this point.
And this is another point of not so subtle bashing rather than discussion.
The real advantage is that for the vast majority of divers diving today, anything beyond cramp removal and tired diver tows are not required. They fall decidedly into the 'nice to have' bucket.
Disadvantage: The PADI OW diver dives with minimal training. S/he is not in a position to adequately perform the role of a Buddy (the rescue of the buddy, if this is required).
If this is the disadvantage for PADI it is equally a disadvantage of every organization that has a separate rescue course. Unless you wish to contend that all of those other agencies are selling a course which is unnecessary as their students have already been given all of those skills.
You want to discuss differences in philosophy, but even when you post what appears to be an honest attempt to point out some differences, you engage in value pronouncements that show you really are not just about the discussion. I get that you don't like PADI or their philosophy, but it is possible to talk about something you don't like without making subjective value judgments which make furthering such a discussion more difficult for anyone who would choose to engage you rather than merely agreeing with you.
How is it that the skills in the standards are not being taught "well as it should," yet the same instructors have time to teach skill-sets outside of the training program? 
