alternatively they could hypothetically just remove it during routine maintenance. Also its rather unlikely that they'd really need to use the ladder- I rather doubt people are scaling sculptures to slap them on things. it's going to be mostly in reach of the ground.

A bigger problem is that most cities and towns will have an ordinance requiring immediate removal- meant to combat graffiti; and while most cities won't be arsed to follow the ordinance themselves when Karen calls... well, it's just less annoying to send the dang truck on a special job.