It's kind of funny though...it's so easy to catch when others make the mistake of their/there - write/right - to/too etc... I can always catch them, when it's my own writing, it's so hard to catch - no matter how many times I read and edit. I think I've caught them all and then I'll look a week or month later and notice the ones that I missed.
So with the many errors of my ways, I really can't say I have any writing pet peeves. I work with a group of people, however, who will notice EVERY "i" that I don't dot or EVERY "t" that I don't cross. So much so that they totally don't pay attention to the subject matter because they are too busy trying to get back at me for mistakes so they can have a "gotcha moment" to they point out to me. Not a lot of errors mind you, they are just looking for ONE!
Since I'm an editor I do my absolute, absolute best to catch mistakes, read-edit-read-edit. If I ever write a book - I will definitely need another editor to edit my edits
I have a friend that can NEVER put the right "there" it used to drive me crazy to the point I just wanted to scream at her, but then I put it in prospective and now...
I can definitely see why we would want the writing in children's books to be error-free. That takes me back to the read-edit-read-edit thought