from what I gather from what you are saying that these issues are prevalent in the US as well so again then what is the issue for Jerusalem Rabbanut Mehadrin(milchig restuarants) if one relies on OU and stark K in the US etc...?
why is it on the bottom of the totem pole on these lists posted here?
There are certain individual items that the rabanut may consider simple and allow as such while others hold it isn't as simple (example canned goods from different countries)
Not to get controversial but there is often a financial incentive for a private hechsher to not recommend another
Additionally some people do not understand that different cities have different standards and lump all together
Remember just because Jerusalem mehadrin has one standard doesn't me ashdod etc has the same
I will also remind that non recommended does not mean not kosher I can state for a fact that when certain private supervising services come into a Jerusalem mehadrin facility not only don't they kashera but they even allow existing product to be used (as long as it doesn't contain specific products they have an issue with)