Could have, could've, could of

So I finished all the books I'd brought home and started on some J.A. Jances that my sister had left here. The protagonist, Sheriff Joanna Brady, corrects her daughter's grammar at least once per book (so far). I've merely rolled my eyes at the futility of it, but this one takes the cake:

"People were in danger," Joanna answered. "I was afraid someone might get hurt."

"It could of been you," Jennifer shot back.

"Could have," Joanna corrected reflexively.

"Have," Jennifer repeated woodenly, scowling.

First, I'm with Jennifer. There's (probably) a time and place for correcting your daughter's grammar, but not when she's just seen you almost be killed - like her father was a couple of months ago.

And second (or Also!): Sheesh. Does Joanna really not pronounce "could have" like "could of"? Jennifer is going to sound like a pompous twit.

As T-Rex said to Utahraptor when the latter caught him "using the wrong it's": Noticing such things in spoken language is impossible!