well, i'm very sorry to say so but i'm afraid i must agree with those who cannot see the situation from your own point of view.
Learning will nearly always result in mistakes - no matter who is teaching or who is learning. So, to have not taken a seam ripper or stitch picker along was not a wise choice. That choice was apparently based on an unfair and realistic expectation which you imposed on the teacher.
Unless I was specifically advised in advance that i should not bring pins, i would automatically take those along, also. (I happen to be a "pinner". If i was sufficiently skilled to never need pins, then i would have chosen accordingly.)
I think it's more realistic and practical to arrive on time for a class and to arrive with extra supplies in case i make mistakes from which i cannot recover easily or quickly. That's what is most practical for my own needs and more courteous to the instructor and other students.