It's very easy to say things like the police should "do something" and "somebody must know" something.i
It is actually incredibly difficult. I'm not going to bang on about staff shortages and cuts because that's done to death.
Bear in mind there are is likely to be one or two officers working anyone area dedicated to problem solving. ( a rough problematic priority neighbourhood and the team is now one officer down from 6) They only work 40 hours a week, so roughly one fifth of the time. If it's like where I work the response cops (who you usually see driving the vans and cars) will have no down time to patrol or be pro active. There is usually a queue of incidents that need attending 4-5 times the size of the available patrols . The last time finished a shift there was approaching 30 open incidents need it attending and 5 patrols which were already engaged. Should a blue light job come in then officers will be diverted from what they're already dealing with. Mostnof those incidents will be domestics of some description, concern for welfare, missing kids (often LAC) and that's before you get on to the stuff that's dealt with in the phone and fed back in behind the scenes (it's not like the fire service where officers are in the station waiting for the bell to ring - not intended as a slur on the water bobbies).
There is no burglary unit, robbery unit, proactive team, divisional tasking force, etc.
Each of those officers will have a workload of 15 or so investigations they're dealing with each with lines of enquiry to follow, statements to take, suspects to trace and interview (people often aren't arrested these days they're asked to attend for interview and arrested I they don't - remember kids you can go to jail without ever actually being arrested).
Going back to your trolly wallies, short of being there when they throw the trolly you're struggling. They'll tend not to throw them whilst someone is there, least of all someone with a pointy head and a bright yellow coat.
Which while a result in so far as you've preventes it you can't simply can't stand a cop every 300yds along the line.
Many years ago we ha an issue with arson in an area of 4 blocks of terraces. I ans a colleague spent 4 nights walking these blocks in random patterns, to our immense frustration three fires were lit (bushes, rubbish, empty house, cars etc). We eventually got someone but that came about by an unexpected route unconnected with the massive effort we put in.
CCTV is seen as a panacea, it's not. Even the most expensive CCTV is easily defeated by a 50p hat or hood. People know it so put their hood up and don't give a toss. It's often in the wrong position, to high or blown out by lights. It's use as a detection tool is limited to someone recognising the person on the cctv (facial features / distinctive features are needed not simply they're wearing the same addidas trackies and Nike Air Trainers that Billy La'scrote was wearing last week).
Forensics are not like on the TV, you need a decent smooth clean dry surface for a fingerprint assuming all the is present (most likely the handle of a trolly) a trolly handles will be handled by thousands of people and have thousands of prints. Those pulling it out from under the train will likely add some too, chuck in contamination and heat.
Fingerprints need, recovering and analysis, not something that happens in 30mins of the bill.
Fingerprints like DNA need the owner to be on the database, with young kids it's unlikely.
Crimestoppers and the likes can be a double edged sword. People have a tendency to phone up and say things like "Dave Smith did a burglary" or "John Brown is growing weed at his house, he has a blue car" which is lovely but pretty much useless, which dave Smith? which burglary? how is this known? etc etc.
Even if a name is given without something more to back it up there will be little chance of a successful prosecution.
I dare say the local force, drowning in its own incidents will simply say this is a BTP issue.