Re: Regards the UK...
The difference between filth and erotica has always been the person consuming it.
I imagine it can be both hence "down and dirty." Contemporary smut's greatest offence is the total lack of imagination or originality but then I suppose just reflecting reality.
It does seem that the media and politicians think that AI image generation is just an advanced form of collage, in which case scissors and glue are the next target.
The juxtaposition of the words "politician" and "think" is ungrammatical in the extreme forbidden by syntax and unsupportable by any assignment of semantics. Mention "collage" you get at best "What? Oxford or Cambridge?" You're a braver man than I if you're contemplating exposing these wallies to scissors and glue.
A simple Gedankenexperiment is to imagine an AI based application that amongst other things can synthesise legal NVE video footage.
So far so good as this already exists in some form - I imagine the spontaneously sprouting extraneous limbs and appendages can only keep things fresh.
The human cast being machine synthesised could be parameterized by skin, eye and hair colours, height and weight, vital statistics† ... you get the idea but wait and... age so that merely changing 18 into 17 you cross this ridiculous line.
So much of this nonsense is perilously close to Orwellian "thoughcrime" but I suspect Blair's premonitory warnings are instead today's playbook.
† eg ginger hair shingled bob, diamond face, green eyes, 180cm, 90-60-90cm, 68kg, 27 years etc etc or whatever melts your butter.