Graffiti is often a sort of cultural infection - once it starts, other people soon join in.
I spent a fortnight in Amboise, in the Loire valley in 1990, there was almost no graffiti anywhere, and what there was was in English.
There is a road right through the middle of Stoke on Trent, the A500, known locally as the D-Road, from its shape on the map. It has large areas of concrete that are the perfect 'canvas', yet they remain completely graffiti-free after more than forty years in a deprived, inner-city environment - though, I'm sure that, if some appeared, it would all soon be covered. I'm quite careful who I mention this observation to...
Many years ago, I painted a bird hide on a nature reserve - there was a particularly well-executed piece in the middle of one wall, involved a bird motif - so we painted a 'frame' round it and left it, to much disapproval. But, as I predicted, no new 'art' appeared for over six months - I'm sure it would have been (re)plastered in days, if we had covered the whole thing.