There's an answer, but it's pretty icky.
Women tend to pay attention because there's no aiming system at all. And is why they get so miffed when you leave the toilet seat up, because they fall into the bowl.
Men have a fleshy hose that folds in on itself when not in use. When it's re-used, it may not uncoil properly first, therefore sending the product in a direction unintended. As we're not paying attention though, and are usually looking down on a dark floor; it's easy to miss potential splashes in case you go looking.
A side effect of this is that men will often start flushing half way through the operation, and try to beat the flush finishing to finish off.
This is also followed by flatulence, yawning, stretching and all the other things we're not supposed to do in the company of women.
I've heard that this might not be only men though...
TL;DR: We're aiming on full-auto, you're aiming snap-shots.