I take our dog for a walk every morning in the cemetery near us, not many knocked down graves in this cemetery, there are a few, but then some are over 150 yrs+ old.
They did tie a note on each grave, yes - each one, there must be a few 1,000, saying that the grave was leaning and not at 90 degrees
and if you're the owner of the grave you should get it attended to, but months later all the notes were removed.
I think it comes down to tracing the owner of the plot. Many have died or they are not able to locate the person responsible for it. People should enter at their own risk