Realistically, I don't see ANY skiers/boarders coming into the landing zone on the larger M, L and XL kickers willy nilly. Most parks I lap you can't even get to the LZ without taking the air or going over the knuckle.
I suppose a person could duck the rope with speed and carve back up into the LZ, but I have yet to see that happen.....because there is no point to do so.
I actually find the park WAY safer and controlled than on mountain. Park etiquette is usually very good, there is a natural flow to the features and people partaking generally know how to handle themselves. And it has to be given pretty much every decent kicker is hit with a blind LZ (nature of the beast). However you CAN see down the jump line and when you can see the person in front of you hitting the next kicker (and pretty much no way for anybody to get into the LZ) 99.9% sure you are good to go. Can't see the person in front exit the LZ...chances are they bailed. Wait a bit until you see them clear.
I mean the same thing can be said about CLOSED race/training courses. However I guess some DB could've ducked the netting so you can never be 100% sure somebody isn't going to be in your way.....
In a perfect world I suppose you'd have a spotter on every feature in the jump line....however finding 5 friends to spot so you can do one lap just is not going to happen.....and frankly isn't required either.