Alarming signs of humour in high places

What the actual flip? (Euphemism)
There’s a Church at the start of the London Road in High Wycombe just opposite my block of flats which is just before the London Road begins. And once again some drunken lackwit has demolished the low wall that separates the grounds of the United Reformed Church from the pavement.
This and similar incidents happen with monotonous regularity, not just at the festive season but all year round. Normally during the night when the roads are empty of most traffic and a fool coming from the roundabouts nearer to the centre of town can gain a bit of speed, come around the bend and… lose control and ram into something.
I normally sleep through it nowadays and awake to find that walls, signs, bollards and anything that might absorb the impact has been knocked down again. Heaven knows how many times the zebra crossing has been taken out of commission.
I stopped by the United Reformed Church to tut-tut at the damage and actually read what the tape wrapped around the damage said.
IDIOT. In bold black on yellow.
When did they start doing that?
Does it have any legal significance?
Are police… no actually it would have been fire and rescue people since their tape was also in evidence anyway are The Authorities allowed to defame people like that without a court verdict to sustain it?
Not that I disagree with the sentiment you understand but I have an appetite for legal niceties.
Enquiring minds want to know.