I don't disagree that members of the public break the shelters and seats etc.Bryn, you missed fleas off of your list, a major problem on buses, just ask the guys who have to return the seats after they get vandalised daily, yes daily.
As for the bus stops, maybe they cannot keep up with the many that are being damaged. Now who to blame for that, well the people who do the damage, not the people who fix it.
Now these people who do the damage they are members of the general public, hold on, but so am I.
Must admit the only time I use a bus is the fantastic park and rides available in some cities.
Regarding the shelter though, years ago we had a solid shelter, made of steel poles and a steel roof with a solid wall on one side. It was never vandalised, it never blew down in the wind. To my untrained eye it looked very secure and stable. Yet the council in their wisdom took it down and replaced it with a piece of plastic rubbish that could fit half the number of people under it and is prone to damage, natural and vandals.
But when I pay my council tax and pay to board a bus, that is not my problem. I should not have to suffer because of others; perhaps if those caught doing things got some punishment instead of a slap on the wrist they'd stop it or deter others.