The difficulty is, no-one equates the results of what they do with the final effect.
If one hundred thousand people flush one nappy down one toilet once a week, individually they can imagine that it will have no effect, because we have an efficient modern sewage system.
The problem occurs with the build-up of that massive amount of wastage, combined with all the other wastage, and again, people do not think ahead to the consequences, because human nature is not to bother with such notions.
Education is the answer.
But since we haven't yet managed to educate any generation that excess drugs and alcohol, and speeding in a car, and being bigoted against strangers, and carrying knives, and so on and so on ... are all wrong, and all carry far more lasting and devastating consequences, what chance do we have of educating people not to drop a wet wipe down a loo?
Not much!