I live close to the scene and there were would have been few illegally parked vehicles.
The crash scene is close to and parallel to the main A27 road - at it's furthest point the crash scene is no more than about 10 metres from the road.
The crashing aircraft had strayed from its route or should simply not have been where it was when it crashed.
It's true there would have been nothing stopping people walking to the spot. I've done it myself in past; likewise there would be nothing stopping people going about their lawful business walking past on their way wherever.
Indeed I would have been doing nothing illegal had I decided to walk in the area on that particular day.
It is not those who happened to be where they were that are in any way at fault; indeed if anybody is.