Some medical students have no interest in obstetrics so trying to convince them to hang around for hours of labour is sometimes hard. Of course they should always (and mostly do) treat women with respect and not just expect to pop in for the last ten minutes.
But they do need to prioritise where they need to be, they have teaching sessions scheduled throughout the day they need to go to, they might decide to go back to accommodation and try and sleep and come back for the night shift.
The best support I have ever seen anyone give a woman in labour (and I include midwifes, midwifery students and partners in this) was from a medical student seeing his first birth. He stayed with that woman for hours (she had no partner). He held her so she could squat, he helped her to the loo, he changed incos, he got snacks, he held her hand and encouraged her all the way. We all cried when the baby was born, the bond they formed was amazing and yes she did name the baby after him (middle name I think). He was amazing and I told him he’d make a great midwife or doula.