IMO there aren't enough police, this is part of the problem really..
In reality, you could have real police officers, or a specialist branch of "enforcement officers" whatever you want to call them, doing this exact same job - baiting paedophiles/child groomers/etc into meeting up, where they're then dealt with. The main difference is that it's a professional outfit operating undercover, regulated, trained and paid - rather than a bunch of blokes running around in custom printed T Shirts with "BARRYS NONCE BASHERS LTD" written on them, whilst brandishing their phone cameras.
Where frontline services are being endlessly cut, fewer police, fewer backend staff, with government ministers endlessly manipulating targets and statistics to simultaneously save money and improve service, to me the focus isn't on trying to keep the public safe, it's about people government ministers keeping their jobs, rather than coming up with solutions.
Ask yourself this, if these naughty old men were evading tax, rather than grooming children - how long do you think it would be before their doors were being smashed down?