Suppose a man enjoys shooting. In particular, he is into "blind-shooting", in which he shoots in conditions of limited visibility: he sets up a target, along with a mechanism to wave a rattle directly in front of the target, and he aims based upon his judgement of where the sound is coming from.
He is unable to afford an area of private land in which to practice this sport. Instead, he goes out into a public right-of-way area at night to shoot. This is of course a grossly irresponsible sport. We might like to say that, given the risk of hitting someone, there is a strong reason for him not to shoot. Of course, if he could be utterly sure that no-one was in the vicinity, then this reason would go away.
It is simply false to say that if there is a person who could be hit, he has a reason, and if there is not, then he lacks a reason. The reason for not shooting comes from his personal, subjective inability to confirm that no-one is in any danger of being shot.