i called the OU today (3/10/16) to ask this very same question, and the answer i got was not amazing. They said that their normal certification for normal kosher for passover for flour is only "guarded" from kneading as you've said. i asked what about the opinion that you can't use normal flour from the market since water might have come into contact with it at some point. He immediately put me on hold for several minutes and then returned to say the following.
That the wheat is cut as normal (as in, the wheat could be rained on after it's cut), and then it is taken to the mill. And that the mill has mashgachim there, and so it is always supervised until it reaches the matzah factory, and once it reaches the matzah factory it is guarded from kneading for the purpose of the mizvah of matzah. When i asked if he could tell me for sure the entire mill was a dry process he said he was not there so he could not say for sure. i asked him for the information of the mill or the mashgachim that were there so i could verify, and he said that information was confidential and could not be shared. And we went back and forth a few different ways and it always boiled down to confidentiality. When i asked him if the mill was a dry process he said yes, but did not indicate that this process was different from how any other flour is treated or processed.