Marriage proposals can be a tricky thing to plan. There's always a little risk involved, especially if you're doing it in public. You never know if there will be some clueless person in the background of your photos or if the fire alarm will go off in the restaurant. You can't ensure a moment will be perfect, but you can be comfortable knowing that most people won't intentionally ruin your moment. Nobody will scream FIRE in a crowded theater because they see a guy getting down on one knee in the audience after the show. Well, almost nobody will.
One entitled hiker is getting roasted on Reddit for sharing their story of ruining a couple's proposal. They decided to plop down on a particularly beautiful spot on the trail to enjoy a large meal by themselves (they claim this is their hobby). When a photographer asked them to move because a guy was planning on proposing to his girlfriend at that spot, they refused just for the sake of it.