People do that all the time. For undergrad, grad, and med schools. And it's not always benign, either. Sometimes people with vastly inferior qualifications get into institutions they shouldn't.
I personally didn't, though I didn't have any connections to "use" so to speak. Would I have? Maybe. That's why people do it. I'd like to say I wouldn't, but the truth is that everyone says that. You don't know who you really are until you are challenged to make difficult choices. Most use every advantage they can in this world, regardless of the moral implications.
That being said, if you get into school that way, you need to live with the notion that you didn't do it on your own--that *maybe* you wouldn't have been good enough if Chief Surgeon Daddy or Mommy hadn't put pressure on the admissions office. People with character and integrity find it very difficult to be at peace with themselves under those circumstances.
I'm happy that I'm going to a state school for people who are of similar intellect and abilities. I got in on my own, and the school fits me. If I had used connections to get into a place like Harvard or Yale, I don't know if I would be happy with myself. If I had used connections to get off a wait-list, however, that might be a different story. At least then you know you're qualified enough to hold your own.
Point is: happens all the time. That's how people get ahead in this world. It's life.