I camp mostly in SPs, and in most of them, very little tree trimming is done. I would like to think this is due to keeping things natural, rather than lazy park employees.
I try to camp during the week, as most parks in my area, are reserved sites only, and full every weekend, or holiday. My site choices are good, but often limited by low branches.
I see many FWs taller than my 12' 6", just drag the branches over the roof, or down the sides. I may be too cautious, but I will always settle for a less desirable site, than risk the damage.
I guess the taller rigs, do the trimming, for the smaller ones.
Jerry