Earlier quoted context omitted.
The problem lies on the wide margin of interpretation those laws give the police. 50kph is a number. "Sexualized drawings of children" is certainly open to discussion.
I know it's HN and we love her numbers but legislation that requires interpretation by judge or jury isn't at all unusual. There are also several layers of oversight and courts of appeal in the UK, which are separate from the government.
There was at least one case where prosecution never, ever, seen the evidence of supposed CSAM found on accused's computer, and if not for the lucky person having a slightly less overworked public defender, they had high chances of being found "guilty" if of minor offense for having what used to be staple of family photo albums - photo of the toddler grand-kids playing in kiddy pool, which was reported by computer tech at a laptop repair business.