Even in forces where there aren't specialist rape units, the rape investigations will still be dealt with by accredited detectives who have further training in order to deal with rape victims. Rape victims require specialist interviewers - it's not a job any old police officer can do.

As above - the training is already in place. College of Policing has lots of information on the training and what makes rape investigations different. There's a whole handbook called ' Achieving Best Evidence ' which is extremely detailed.

The culture is more of a media creation. Sexual offences and domestic incidents are priority investigations as they are so risky from a safeguarding point of view.

The issue with getting rape cases to Court has already been covered in the thread. Unfortunately, the vast majority of cases come down to one word against the other with no corroborating evidence. It's so difficult to prove, therefore the CPS won't charge