Sorry to hear about the scores. As a parent if a former public school kid, I totally get where you are coming from. But don’t get discouraged!
My theory would be that it is two things: (1) there is a very small subset of students who take the ssat, most high-achieving. So a high performing kid compared to the regular population in public school (or private) is not necessarily going to be a top scorer compared only to other high performers. (2) On top of that, lots of those other high performers have spent a lot of time preparing. In that context, your daughter’s score, taking the test blind-cold, is very respectable.
Have her take some practice tests and tackle some of her weak spots. She can do this! Also, she doesn’t need to be in the 90th percentile to get into great schools.