The question asked her to write 5x6 as a repeated addition problem, so DD wrote "5+5+5+5+5+5=30". The teacher counted it wrong, saying she should have written "6+6+6+6+6=30".

I guess she could be concerned that the student didn't understand that "5 times 6" litterally is 6, five times, but it sure sounds like the teacher doesn't understand the nature of multiplication. I hope she does, and is just assuming that you give her enough credit. Sad that teachers are in the position of justifying themselves on this level. But some have earned that position.
Frowns,
Grimity