Why do you think there is such a stiff penalty for disobeying instructions in "A Sound of Thunder"?

There are two reasons for the stiff penalty for non-compliance with the instructions of Time Safari, Inc.:

1. The company receives tremendous fines for any infractions, even possible government action. Moreover, the company could go out of business as a result of such consequences.


2. The "butterfly effect" could occur. This is the concept that all things in life are interconnected and are dependent upon initial conditions. That is, if there is a small change in the state of one thing in nature, large differences can occur in a later state.

Further, the ending of Bradbury's story serves to explicate the impact of disobedience of the instructions of Time Safari, Inc. For, Eckels's having stepped off the anti-gravity path causes a butterfly to be killed, and he unknowingly brings this butterfly back on to the present on the bottom of his shoe. When he enters the office of the company, he is shocked to see that the sign is markedly changed, 

Sefaris tu any yeer in the past.
Yu naim the animall
We taekyuthair
Yu shoot itt. 

With trepidation, Eckels asks who won the presidential election hoping to hear that Keith is president and nothing has changed, but a man he does not recognize answers, 

"You joking? Who else? Not that fool weakling Keith. Deustscher, of course. We got a man now with iron guts!"

After learning of this profound effect of his mistake, Eckels begs to take this change back, but such cannot happen unless he does not live. Then, he hears "a sound of thunder" as Travis, who has cocked his rifle, shoots Eckels.