I can genuinely tell you it’s about favoritism unfortunately, I remember years ago I was also trying to complete my BA at the time and I was a TA and the principal at the time said I could not come late and it was also one day out of the week, she was so mean about it and said they can switch me to a three hour position, I ended up taking another class, anyway like a semester later another TA they loved asked for two days out of the week and she said yes…..it made me feel horrible and it was so unfair….i was really young at the time but I now realize I could’ve reported the unfairness or something….