@tom There was a formal shift (am sure you can google about it) as katy above suggests, that the base position should be that all rape victims are telling the truth. Rather than initially treating it as an accusation that needs to be proved.
Evidence should be then looked at to support/disprove this (that the rape victim is telling the truth.)
My impression is that the police are getting sloppy such that if they find a bit of evidence pointing one way or the other they stop looking for more. Particularly if it points towards the crime having occurred.
Of course ‘lack of resources’ is going to be publicly blamed rather that ‘poor police work/not doing the job properly’.