It’s a common trick. They plant a sign right on the property line so that each property owner thinks the other planted it. Maybe tonight the wind will gust and pull the sign up and throw it in the gutter ;)
if it was a house I would sorta understand because most yards overlap with each other, but this is a PRIVATE, COMMERCIAL property that isnt in a main neighboorhood, do the only people who would see this propaganda would be my clients!