That’s just fiction...a real-life Jurassic Park would be run much better than that. /s .............................. If its a Government project.
I still use the JP movies as examples for kids when Silly Hollywood Plots and the suspension of disbelief come up. Assuming the basic premise of the movies, any rational actor would have on call some heavy weaponry capable of putting down the big, bad beasties, a couple of tracked armored vehicles, a reliable aerial capability, some secure safe rooms in strategic locations, etc. It really wouldn't take much, and it would be a pittance given the scale of the park. A couple of Bradley's would handle the ground component. (One to kill the T-Rex, and the other for backup when the scriptwriters make the first one break down.
My other favorite example is monster or horror films where the designated victims split up at the first sign of trouble, usually so they can expand a search of some kind. My daughters used to get frustrated with me for laughing through these kinds of movies. I always told them that people that stupid deserve to die. They're old enough now to take the point.