First, how police treat, and deal with, victims when they first report is an issue. Over time, we've seen some improvement in the way police officers handle cases.
Where things really get difficult for victims is at the prosecution stage. Prosecutors regularly tell us that they believe the victim but don't have what they need to go forward. That's a huge barrier. That's where the process tends to hit a brick wall.
In my experience, the first point of contact is extremely difficult for victims. They have to answer the police officer's questions and what have you. The human element would make a big difference in terms of how the victim is treated initially and what happens next.
A number of barriers exist. I'm not sure whether that fully answers your question.