It seems like they are not in the game.
Security was introduced into Planet Coaster 1 in a later update and tbh a lot of people didn't really like the way it was implemented. It was more of a chore rather than anything that improved the actual gameplay.
I suspect it might be one of those things that gets brought in with a free update or DLC once they have a bit of time to work on other features rather than getting the game ready for launch.