Most children are potty trained by 4 years old and are using the toilet by themselves and no longer needs diapers during the day at least.
During the night the 4 year old might need to wear diapers for bed wetting but during the day most 4 year olds are not wearing diapers anymore and are potty trained.
However some 4 year olds may not be using the potty yet and that is normal as all children are different and potty train at different ages.
But if the child is getting near 5 years old the child needs to be getting potty trained and out of diapers since the child cannot attend kindergarten wearing diapers and not being potty trained.
Unless the child has special needs or is medically required to wear diapers the child has to be potty trained before going to kindergarten.
Most kindergarten kids will be out of diapers and be potty trained.
To go to kindergarten the child must be potty trained and using the toilet before school and they must go to the bathroom on their own unassisted.
If the kindergarten student is not potty trained then they won't be allowed to attend kindergarten unless they are special needs or have urinary incontinence and have a medical reason to wear diapers to kindergarten.
But if the child has no medical need for diapers then they won't be allowed to attend kindergarten if they are not potty trained.
Teachers will not wipe bottoms or change diapers because they are not allowed too but a nurse would change the child's diaper for the kid if they are in need of it.
Teachers are not legally allowed to wipe children's bottoms or get anywhere close to their private areas because they could be accused of molestation or touching a child in the wrong place which could get them into trouble with the law.
A school nurse however could help a child cleanup if they have an accident such as if they pooped their pants or peed their pants then the school nurse could assist the child in getting cleaned up.
However a 5 year old or 6 year old child should be able to properly wipe their own bottom and change their clothes and underwear.
If the child is in pull ups they should be able to put a new pull up on as well.
If a child is going to school they should be wiping their own bottoms as well as changing their own clothes.
I remember being in Kindergarten and I had pooped my pants due to diarrhea and my parents brought me a change of clothes.
I cleaned up myself and used a shower we had in the school to take the shower and then changed my own clothes.