You should check your property deeds or survey map first!

這類問題我聽過許多次，許多時候是個人土地侵占公共用地或鄰居土地。

I'd better explain everything in english. As a Civil Engineer in Land Development, I got involved in so many land encroachment issues. Through the survey map and deeds, we can solve most conflicts. Most of the time, it the private property owner encroach the municipal property. Like this case, you shouldn't install the basketball facility into City Street Easement (30' from the center line fo the road). Why the city code enforcer or department of public work didn't notify you so many years ago. You got a good question. I guess they don't have time and energy to do each lot survey or too lazy to care about it. But one day, they start to revise their city map or county map and any utities record maps, they will find it and sue you to remove it. Usually, they can give you a little more time. As for the third question, it doesn't work for you. You don't know the other people's property information and you cannot tell they encroach public propety. Don't show me the photo, it doesn't work from a professional point of view.

At last, you can challenge the city. But you need find a lawyer and spend some money to dig relative information which definitely cost you more than $300. But if you have licensed survey map shows clearly that the basketball rig is inside of your property, you definitely should sue the city and get money back. Good luck!