We had this last year, but with LSE, UCL and Warwick. DS would not have been that upset about his Cambridge rejection except he had no other effective offers. (His fifth choice changed their course making it less attractive.) He did not hear from any till mid-March. Fine as it was an offer from LSE, which he wanted most. Warwick bizarrely offered him a course in a different department, something which Durham have apparently been known to do, and UCL rejected him.
Looking at Student Room over-subscribed Universities have a problem. They have to give all EU applicants equal consideration, so need to see who has applied before making final decisions. DS knew someone who received an early offer from Warwick for the same course, but thinking about it he had fluency in another language which may have boosted his prospects at a University with a big Erasmus programme. Your DD should not compare herself to others. The differences in applicaitons will be small and it is impossible to guess what selection criteria each University is using.
Applications will now be in and those with Oxbridge acceptances will be firming their choices, so there should be some movement soon. Then it becomes a long wait as universities try and fine-tune offers to available places. It is very distracting for applicants who are both young and trying to juggle mocks.
DS' course will have attracted a large number of EU applicants. What seems to have happened is that some, whose home educational systems do not provide sufficient differentiation plus mature students with non standard qualifications, were then set an additional test. Only then did things start moving with the pool of remaining candidates being whittled down slowly. With LSE, acceptances were issued on Thursdays and rejections on Fridays. Each week, with no offer on a Thursday DS had to wait nervously through the Friday. According to TSR, the rejections stopped at 4.00pm so then and then only then could he breathe again.
It was really horrid. Oxbridge and medical schools applications have an early deadline so they have time to sift through numbers of good candidates. I think this should be considered for other over-subscribed courses.
For what its worth, DS was applying with five relevent A levels and predicted grades included 4 A*s, plus lots of evidence of interest in his subject. Fees, internet or whatever, good students seem to better aware of which Universities offer the best courses, and seem to be working harder, so the competition is tough. Tell your daughter to hang in there. There is a good chance she will hear soon after the application deadliine. If not, no news is good news, and it means she is very close to the standard they are looking for.