Well, you usually get to choose which question you answer from several options and then you get to enter the response to that question. So a hacker would first have to know which question you chose out of say a half dozen options and then would have to know the answer to that question. It's not like pet's names are the only options for questions at these sites.
Here are the options on their list. Try to guess which one I use for my online banking (or if it's even included in these) and then try to answer it. I'll give you... 3,650 tries; that's 10 a day for the next year and I'll bet you still don't get it.
1. What was the name of your first pet?
2. What was the make of your first car?
3. What was/is your best friend’s first name?
4. What is your mother’s maiden name?
5. In what city were you married?
6. What is the first name of your maternal grandmother?
7. What is your favorite hobby?
8. What was your high school mascot?
9. What is your birth date?