Some people just don't have the patience or humility to be a good, loving parent. I have never seen a mother do that but it would make me really sad. She must just be really unsatisfied with her life and is just taking it out on her daughter. My mom can be a little brutally honest sometimes but she always means well.
I think it has to do with the way they were raised. My mother had a tough childhood and so she may come off as incensitive towards us at times. Her dad was overlyreligious, strict, and would beat her all the time. Somehow she still loved and respected him despite all the bad that he did. She used to be that way with us growing up but something happened in her that made her change eventually.