Primary I really feel your post is disgraceful and if I had a small child who had accidents in your class I would be really worried.
My DS1 had a major toileting regression [poo and wee] when he started reception having been completely toilet trained prior to this [with the odd accident].
The school and his reception teacher were not very helpful with this to be honest. They accused DH and I of not having toilet trained DS and made out that he was the only child having accidents [funny then that I would see reception teacher hand wet clothes in a bag to other parents at home time
]
However my sense was that DS was unsettled and anxious in this new unfamiliar environment. Most of his classmates knew each other from the school's nursery and DS had come to this school from another local nursery. He would go into school crying most mornings for about the first six to eight weeks and his toileting accidents occurred at the same time.
Doesn't really take an early childhood degree to work out what is happening but the school and teacher were of the same mind as you primary, that it was not the teacher's responsibility to clean DS up and this was making life difficult for her.
I ended up taking DS to GP to see if there might be anything medically wrong with him. GP was nonplussed at school's attitude and said in his experience of reception age children regressing around toileting was not that unusual... but he referred me to the continence nursing service for more support and advice and I saw this lovely lovely woman who reassured me that DSs behaviour was not unusual for a four year old starting school [and that she actually saw children up to the age of seven where it is not unusual] and that someone from the team would go into the school to see DS in that environment and try to work out if there was a reason he was having these accidents. Apparently children can become fearful of going to the toilet if they associate them with negative feelings, i.e if they once saw a spider in there or it is too draughty, etc.
However, she also said the team would speak with the school and the teachers and offer support around this issue. I could have kissed her as I found it very difficult to speak with the teacher about this issue at this point, the only feedback I was receiving from the school was that DS should be toilet trained and he was the only one having these accidents 
Anyway OP, sorry for the essay, but I just wanted to say please don't stress, your DD won't be the only one having accidents at 3.5. By all means get support from your GP and/or a continence nurse as I imagine they will put your mind at rest and may also be able to offer some advice around what to do next.