I think you really overestimate the capability of the UK to enforce laws. Yes, they can write them and yes they can fine large corporations, that's basically it.
They cannot enforce laws against such "petty" crimes, the reason society mostly functions in the UK is because most people don't try to break the law.
Pretty sure the local punters would kick the cops out if they came for one of their own, especially if he got them their porn back.
> They cannot enforce laws against such "petty" crimes
No, they aren't interested in enforcing laws against petty crimes. The establishment literally don't give a toss if someone breaks into your house and nicks your telly.
They are very interested in enforcing the kinds of infringements we're talking about here.
What do you mean? They already arrest thousands of people a year for posting (or even retweeting) things online in the UK.
What makes you think, if the Gov was to implement some sophisticated DPI firewall that blocks a million different things, they won't come after the people who circumvent it? They already enforce petty crimes. I could report you for causing me anxiety and you would have a copper show up at your door.
It's not just about UK abilities to enforce laws, but also about other factors. The described activities are extremely unattractive as criminal: small market, small margin, the need for planning, preparation and qualification.
There is no need for special efforts to enforce the law. Put a few people in jail - and everyone else will quickly find safer and more legal ways to spend their time. No one will do something like that unless they are confident of their impunity.