Why does this make ME feel like the bad guy? [View All]

We live in a lower-end neighborhood, with a ton of kids around... I don't know which kids belong to what house, even. The kids next door tend to leave a lot of their stuff in our driveway, which I generally move, instead of running over when I get home. *sigh* I don't much care if they play in our driveway, but tonight there were 8 or 10 of the older kids (ages probably 8-16) running in, around, and through our backyard, playing tag. Our yard is fenced on one side and 1/2 the front, with retaining walls along the back and other side, so it's not like it's part of a large open space. They have to run right along the side of our house (literally about 24" wide space) to get to the backyard, yelling, etc. So after poking my head out there the first time, when it happened again, I went out and stopped 5 or 6 of them to let them know it's private property and to not play back there. The question is, why does this make me feel like a curmudgeonly asshole, that their parents didn't teach them to respect other people's space? *sigh*