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.
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.
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.
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.