Simply put, people getting killed by animals adds nothing to the game. It's not a feature nor a mechanic. As has been said before, animals can escape and threaten the guests. This impacts both the building and management sides of the game. That the animals can escape means your habitats aren't secure enough, and that they threaten and scare away the guests will hurt your zoo's reputation. Graphic violence would not be necessary, and does not fit the vision of the developers. That would mean that any violence would be needless and inappropriate, and that is the worst you can do in games like these. This has nothing to do with maturity, what another game did, or realism. Some games may need graphic/comic violence to convey a certain meaning or experience, and that adds to the experience. In these games it adds nothing. Sure it may be "fun" to crash roller coasters or let animals escape, but again it would be needless and senseless.
If you want animals killing guests, play Jurassic World Evolution. In that game it does add something, as that is the whole thing about the Jurassic Park franchise: dinosaurs escaping and wreaking havoc.
If you want animals killing guests, play Jurassic World Evolution. In that game it does add something, as that is the whole thing about the Jurassic Park franchise: dinosaurs escaping and wreaking havoc.