Wiping is the last skill, not the first. Most children master the sequence — go to toilet, manage clothing, wipe — in stages. Independent wiping after a bowel movement requires fine motor coordination and spatial awareness that most 2–3 year olds don't have yet. Being toilet trained does not automatically mean being able to wipe. These are separate developmental milestones.
What most daycares are expected to do: Licensed childcare centers in most states are required to help children with toileting needs, including wiping, as part of basic care for children under a certain age (typically 4–5, depending on jurisdiction). A 2.5-year-old who is trained but can't wipe falls clearly within the scope of care that daycare staff should provide.
What to do if this isn't happening: Talk to the director, not just the teacher. Frame it as "she's not developmentally ready to wipe independently yet — can we make sure staff are checking after bowel movements?" Most directors will respond to this as a care issue, not a complaint.