It’s certainly not a new phenomenon, you can see it even in infants barely able to walk yet and in toddlers…
I would guess what ever drew you to that spot was more than just solitude, even if that is a primary reason… and I would guess the same thing other than solitude draws others as well…
I tried to think of a time when it seemed I had an entire area to myself I picked the worst spot in the area to guarantee it… what I came up with is never…
I guess if it bothered me enough I would just talk to the guy when he pulled up and before he parked, and would most likely do the same if I returned from a hike to find him there… there is no reason to be un-neighborly before knowing the guy or his thoughts…
What is relatively new is the means to rant about it to such a wide audience…