Who has been fined for feeding ducks where it has not been specifically prohibited? Whether we like it or not, private contractors are paid by local authorities (and railway companies) all over the country to enforce all sorts of things as the police are not everywhere at once - it doesn't make littering any less vile. Obviously, private contractors simply need to be trained and be aware of their limitations. They either have been granted the authority to enforce the law or they have not - if not, then they simply shouldn't be there. Assuming they haven't just turned up out of the blue to collect random fines with no authority, then they are doing nothing wrong if they follow the requirements set out for them by their employers.
Dropping cigarette ends (the subject of the thread) doesn't fall into any 'grey areas' as far as I am concerned.
I mentioned it in a previous post about a lady in Maidstone being issued a ticket for feeding the ducks, the council promptly cancelled the ticket and the subsequent publicity about the incident, on top of other complaints, lead to them suspending the contractors.
No doubt the lady was seen as a nice easy target, and this is what happens when laws are enforced by anybody other than the police and this includes ticketing issues on trains, they tend to be enforced inconsistently. A law abiding sort of person who will accept the fine and pay it without argument are a dream come true whilst a foul mouthed yob who will tell them in no uncertain terms where to stick there ticket, well they are just are just far too difficult to deal with.
As I said previously I don't condone deliberate littering, and I don't include somebody who clearly dropped something accidentally, but two wrongs don't make a right.