Why do people walk across other peoples pitch

Location?

Because that is what you find on the majority of Caravan Club Sites and this forum is mainly read and posted by club members. Some people actually prefer it that way. Each to their own.

Plus I don't necessarily "grumble" about open plan site. If I know what I'm booking then I don't have anything to grumble about., except inconsiderate Oiks who want to use the pitch I'm sitting outside having a beer and relaxing to save 2 or 3 yards by cutting across it, especially at the moment where we are supposed to maintain some sort of social distancing.

We stayed on 2 Independent sites last year and both of those were the same. No hedges. So you may not find your hedge nirvana if you decide to go to a site. Even some CLs are aren't hedge or space friendly.

my photo was taken in Pontorson at the Haliotis site. the pitches are large, well defined and well kept and, as per OP, are rarely invaded.

its a also a great site for lots of other reasons, but the hedging (which is sometimes used just as well in the UK, but i couldn't find a photo) is the thing that gives a relaxing, private pitch.

one site we visit regularly in the UK is Salisbury C&CC (Hudson's Field) which is everything my example isn't...

open field, pitch definition just a marker in the ground, sufficient spacing (per regs) but appears much more crowded with literally nothing between adjacent units, no privacy whatsoever...

however, i agree with TW that members there dont seem too bothered, might be the tenting background and popularity, especially in summer..

We go there for the location (city, cycling, walking, heritage) but really dont like the site much...we often visit with pals who love it....

as above, it takes all sorts...

In the Covid precautions advice CAMC is giving out, "how you can help... keep to footpaths where possible and avoid short cutting across pitches..."

Our favourite Cornish CL (RIP☹️)had individual pitches. The farmer had banked up earthworks, then these were over planted with all sorts of typical Cornish hedging plants and wildflowers. Huge pitches as well, two would easily have taken a couple of typical Club awning pitches. They were easy to make private as well, as one or two had drive in entrances, you could swing round with van inside pitching area, and pitch up however you wanted.  We shall miss staying there this year, sadly back to more conventional fare......

Location Cornwall - and if I’m not mistaken these are hedgedpitches for those who dislike intruders