Its public water. I try to not fish around docks that have signs of children though (float tubes, kids life jackets hanging, swimming beach). They usually aren’t very productive docks anyways with all the commotion. But otherwise they are all fair game IMO.
I think they knew what they were getting into when they bought the house.
I believe MN, WI, IA, and IL all have laws in place if someone tries to disturb you while you are fishing/hunting legally. Call the DNR/sheriff and let them know of the idiot that thinks he owns the water under his dock. A deputy knocking on the door will teach him to quit yelling at fishermen.
It happens all the time on a lake I visit in MN. People will come down and fire up their boats because we are fishing their dock, or tell their fully clothed kids to run down the dock and jump in the water damn near across our lines.
Quite often though when I am fishing a string of docks I’ll have people come down and throw a line in the water off their dock before I get there, usually with no bait. But that is okay IMO, didn’t hurt my fishing any.
They aren’t all like that on that lake though. One guy I can remember very clearly, for a good reason. We were catching some NICE crappies off docks one year, and would hit them every morning at daybreak. Every morning there would be an older man sitting on his deck drinking coffee and reading a newspaper. When we got to his dock he’d say hi and ask if we were still getting them, what we were getting them on, etc. When we caught a fish he’d yell “nice one!!” and wave. Really a nice guy.