I guess there could be different circumstances where an apology might be necessary. I'm thinking of a lot of sexual assault complainants who come forward and perhaps their allegations are deemed unfounded originally at the moment they come forward, but perhaps later on other victims might come forward in the same case, and then a case does proceed against an accused.
I think it could have to do with treatment on an individual case. People want to be believed when they go to the police to report sexual violence. Sometimes they are not respected when they do that, when they go. Perhaps they are not provided with a support person when they are going to have to give a video statement.
Obviously it would be the service itself or the complaints mechanism that would decide if such an apology letter was ever required, but I think it's something we can do for victims.