Here's a nifty little argument I have reconstructed from Elijah Millgram's "Does the Categorical Imperative Give Rise to a Contradiction in the Will?" (republished in his Ethics Done Right, p. 99f).
One chooses a course of action in ignorance of others' rules and policies, and vice versa. (premise)
The possibility that each set of actions is coordinated between individuals is very slim indeed. (1)
It is not feasible to expect that others' policies and rules will deliver the cooperation that one's own projects need from them. (premise)
Therefore, others have to make exceptions for one to exercise his own agency successfully. (2,3)
Millgram spends a paragraph defending premise 1 (see first and second full paragraph of p. 99). I want to suggest that there's two ways of reading the first premise. One reading of the premise makes it a fairly innocuous point - I imagine Millgram is not talking about ignorance in this way. The other reading of the premise makes it a majorly robust point, which, I take it, is Millgram's intent. Let me review Millgram's robust reading first.
He has several points supporting that we choose our course of action in ignorance of others' rules and policies. First, most people do not announce what their rules or policies are. Second, and related to the first, even if most people did announce what their rules and policies are, we are not the kinds of beings who are able to track all of them; we have limited cognitive capabilities, and we are not able to process that many rules or policies at any one time. Finally, he raises the issue that even we do not know what our future ends will be. If we don't know our own future ends, then surely others will not be able to predict what our own ends will be either. All of this leads us to the idea that we are ignorant of one another's rules and policies. Call this the robust reading of ignorance and the reading that Millgram seems to endorse.
I agree that there is a robust reading of the ignorance premise, but I do not think it is the only reading. If it is not the only reading, then the conclusion does not follow. We are still left with the fact included in some Kantian arguments: human agency is dependent on the cooperation of others. Call this the innocuous reading, and I will now give some reasons for thinking it to be an optional reading of premise 1.
We do choose our course of action in ignorance of others' rules and policies, but we are not completely ignorant of them. For Millgram's premise to work in just the way he wants it to, we have to be completely ignorant of others' rules and policies. By completely ignorant, I mean that we know nothing about others' rules and policies. Millgram's first point is that we do not announce what our rules and policies are. I agree, and we do not have to do so because we know intuitively know what others' rules and policies are. When we are at a four-way stop, we know that the other driver knows whoever arrived at the four-way stop earliest can go first. If we were completely ignorant of others' rules and policies, the universe collapses at a four-way stop; we are rendered incapable of acting at all. All of the drivers would stare at one another.
Second, we are plastic enough to be able to adapt to any sort of environment, so we can process any number of rules or policies we may have to confront at any given time. We track all of them, even though we may not be consciously aware of the fact that we are tracking them. Millgram is correct to suggest that we cannot be consciously aware of others' rules and policies, but we can adapt to the environment such that we can accomodate them in order to act.
Finally, Millgram raises the idea that we may not now be aware of what our future ends will be. If he means that we do not know what we will be doing at 11:15a.m. on July 25, 2016, then I agree. No one has even begun to put that much effort into formulating such a detailed course of action. But we can know approximately what our future ends will be. For instance, I know now that I will be planning for a fiscally healthy retirement or helping my kids get into college or continuing to save for that BMW I've always wanted. We are ignorant of exactly what our future ends will be, but we are definitely not ignorant of what our approximate future ends will be.
Since it is questionable whether we are truly ignorant - in Millgram's robust sense - we can only conclude that the fact that human agency is dependent on the cooperation of others still stands, though somewhat more weakly than it has.