The problem here isn't so much a false allegation. The problem is the police's (deliberate?) failure to ascertain and communicate to the CPS this...

...she had posted a false date of birth on Facebook, suggesting she was 17.

Or perhaps the CPS did know this, but went ahead with a needless and doomed-to-failure prosecution out of spite for the poor young lad. It's disgraceful that a 19 year old boy can face years in prison and, in any case, an ordeal such as this utterly misconceived prosecution just for having a bit of a (consensual!) tumble with a girl a few years younger who presented herself as a little older.

That's why I call it an Industry, Randall; many times the main fault lies not with the false accuser but with bent cops, corrupt lawyers, crazy CPS, broken laws.

Ah I see what you mean, dear host. "Industry" is giving it a bit too much credit. We think of productive factories, engineering innovation and, well, industriousness.

I think "scam" is the proper term.