I'm convinced that local officials help in this regard. I sold my house in Reynoldsburg, Ohio a few years ago. I attempted to first "sell by owner". I spent quite a bit of money on some nice signs - simple ones that were not eyesores. I put them out in my neighborhood and they were "stolen" within a couple hours. I found out later that some anal city official doofus confiscated and destroyed them. Wouldn't be suprised if the wimp's wife was a Real Estate agent. By the way, none of the other Columbus suburban neighborhoods have this stupid rule.
Are realtors allowed to put up signs?
So, you failed to check what a Realtor would have known about local ordinances, and somehow the Realtors are the bad guys? There are a number of towns in our area which have sign restrictions, and they WILL ticket and fine you. Agent or FSBO will pay alike for violations. Town governments pass these regulations; why would a Realtor's relative have an interest in restraining the trade?