Why do parents get so mad if their kid poops in his/her pants?

I knew a guy who had a pooping accident in school and his parents yelled at him and grounded him. I realize he's older, and should no better, but why are they so harsh?
Answers

DR + Mrs Bears face

HI so it's not the kids fault if he is ill. just goes to show how ignorant the parents are.

Darko

Because the parents are embarrassed and have to clean it up. they thought the pooping would finally be over at this point.

I know everything

It’s just a natural reaction. I remember when I was 5 years old I accidentally spilled a glass of milk. My parents immediately yelled “why did you do that!!?” I was equally angry and retorted “well I did it on purpose!!!” They were surprised at my answer and dropped the subject immediately.

Cogito

That was ONE incident. Most parents would be very understanding about such an accident. It can happen to anyone, at any age.