Some good answers here that pretty much cover why land owners have the right to keep folks off their property.
And now for some true stories here too...
My extended family (aunts, uncles, brothers, sisters, cousins) probably own about 1,500 acres in total of decent hunting land. We/they always let people hunt on the property, because we figured that if we were not using it...perhaps someone else could get some enjoyment from it. BUT, times of changed....
My uncle saw some archery hunters on his farm one day. Never gave it a second thought. That same evening, he saw some lights in a back field of his. Just as a precaution, he called the police to see what was going-on. It turns-out that those same guys that were archery hunting were trying to strip/steal the parts off of a bulldozer that he had parked there. They had it in about a hundred pieces, with anything they could carry, loaded in the back of their pickup truck. The following week, my uncle posted NO HUNTING signs all over his farm.
On a piece of property I own with my siblings, things simply got out of control. First, the county raised the assesment of the property by 200%; meaning, we are now paying 3 times as much in property taxes for a tract of land that is only trees and brush. ATV riders have making trails over parts of the land. Once they make a trail, the rain comes and washes the top soil away, creating ruts...which makes ATVing harder...so they make new trails...until the land is criss-crossed with rutted trails that are void of topsoil and any sort of plant growth.
My one cousin got it right. He says that the only time that people seem to know him is when hunting season comes along and they want to hunt on his land. He too has been hit with higher tax assesments on his two farms.
Ironically, I also hunt on private property that is owned by some individuals. BUT, here's the thing. Every year, regardless if I hunt on their land or not, I always send them a small gift as a token of my appreciation for allowing me to use their land. In fact, I have not hunted that property for 9 years now, but I still mail them a $20 box of candy or some other reasonable gift to keep in good terms. And, two years ago I got a letter from the landowners telling me that they have posted their property as NO HUNTING...except me. They stated that if I wish to hunt there, I am more than welcome to use their property.
The moral of this story is... Politely ask permission to hunt on people's property. When possible, give them some token of appreciation for their hospitality (a pie baked with the berries you picked, or some smoked fish from the pond you fished out of, or some deer steaks, or a simple box of candy or other momento). It's not about the value of the gift. It's all about the fact that you aknowledge that they are the rightful taxpaying owners of the land and they are being gracious in allowing you to use their property to hunt on. End of lesson.
