I am only speaking from my personal observations and opinion. I have been to a large number of social dancing venues over the years. I have found that the rules on the dance floor vary, depending upon the owner/host and the rules they set. Often, the rules are unspoken, and you have to figure them out over time. But sometimes, the rules will be printed out.
Here is an example at the following link http://www.metronomeballroom.com/parties_f.html of a printed set of guidelines.
As far as a partner anticipating a collision, well, it depends upon what type of dance you are doing. In some dances, like West Coast Swing, the follower has a choice when she is going down the slot as to how far she goes if she sees a collision. This usually doesn't impact the leader too much because they are dancing in an open position. With many ballroom dances, anything the follower does will have an impact on the leader. And certain actions on the part of the follower could throw the leader off balance and even cause a collision.
In my opinion, if a follower feels unsafe on the dance floor because of something that the leader is doing, she does have several recourses. If there is time, she can tell her partner she is uncomfortable and why. If there isn't time, she may just react instinctively to protect herself. If her partner is continually putting her in unsafe situations, she can also decide to leave the dance floor as politely as possible. The fact that a follower feels unsafe on the dance floor may or may not have anything to do with a leader's actions. Dancing with another person, especially in a follower's position, requires a certain amount of trust, skill and self confidence as well. One is somewhat vulnerable and sometimes in certain situations one may be more uncomfortable in certain situations than others.
Usually, I have found it best to deal with the immediate situation in as painless a way as possible for both parties and then later to talk your partner, in a non-stressful environment out of the public eye/ear. Then it is easier to discuss what happened and how both of you would like to handle the situation in the future. The first time it happens, it is hard to know what to do. But, as time and experience continue, it is easier to learn ways to deal with things. However, it is usually something you plan in advance after having done it the way you don't want to do it. It is hard to think and know what to do when an unexpected, never-before-encountered situation occurs. Hindsight is easier...
Certainly patience and forgiveness are helpful tools in any relationship, be it dance or any other kind.
Karen